Protoxin-II variants and methods of use

ABSTRACT

The present invention relates to Protoxin-II variants, polynucleotides encoding them, and methods of making and using the foregoing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Application 62/142,069, filed Apr. 2, 2015, the disclosure of which is herein incorporated by reference in its entirety.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Sep. 7, 2016, is named 400364-20214_SL.TXT and is 481,859 bytes in size.

FIELD OF THE INVENTION

The present invention relates to Protoxin-II variants, synthetic polynucleotides encoding them, and methods of making and using the foregoing.

BACKGROUND OF THE INVENTION

Voltage-gated sodium channels (VGSC) are present in all excitable cells including cardiac and skeletal muscle cells and central and peripheral neurons. In neuronal cells, sodium channels are responsible for amplifying sub-threshold depolarizations and generating the rapid upstroke of the action potential. As such, sodium channels are essential to the initiation and propagation of electrical signals in the nervous system. Aberrant sodium channel function is thought to underlie a variety of medical disorders (Hübner and Jentsch, Hum Mol Genet 11:2435-45, 2002), including epilepsy (Yogeeswari et al., Curr Drug Targets 5:589-602, 2004), arrhythmia (Tfelt-Hansen et al., J Cardiovasc Electrophysiol 21:107-15, 2010), myotonia (Cannon and Bean, J Clin Invest 120:80-3, 2010), and pain (Cregg et al., J Physiol 588:1897-904, 2010). Sodium channels are typically a complex of various subunits, the principle one being the pore-forming alpha-subunit, which is alone sufficient for function.

Nine known members of the family of voltage-gated sodium channel alpha subunits exist in humans, Nav1.1-Nav1.9. The Nav1.x subfamily can be pharmacologically subdivided into two groups, the tetrodotoxin (TTX)-sensitive and TTX-resistant. Nav1.7, (a.k.a. PN1 or hNE) is encoded by the SCN9A gene, is TTX-sensitive and is primarily expressed in peripheral sympathetic and sensory neurons. Nav1.7 accumulates at nerve fiber endings and amplifies small sub-threshold depolarizations and acts as a threshold channel that regulates excitability.

Nav1.7 function is implicated in various pain states, including acute, inflammatory and/or neuropathic pain. In man, gain of function mutations of Nav1.7 have been linked to primary erythermalgia (PE), a disease characterized by burning pain and inflammation of the extremities (Yang et al., J Med Genet 41:171-4, 2004), and paroxysmal extreme pain disorder (PEPD)(Fertleman et al., Neuron 52:767-74, 2006). Consistent with this observation, non-selective sodium channel blockers lidocaine, mexiletine and carbamazepine can provide symptomatic relief in these painful disorders (Legroux-Crespel et al., Ann Dermatol Venereol 130:429-33, 2003; Fertleman et al., Neuron 52:767-74, 2006).

Loss-of-function mutations of Nav1.7 in humans cause congenital indifference to pain (CIP), a rare autosomal recessive disorder characterized by a complete indifference or insensitivity to painful stimuli (Cox et al., Nature 444:894-8, 2006; Goldberg et al, Clin Genet 71:311-9, 2007; Ahmad et al., Hum Mol Genet 16:2114-21, 2007).

Single nucleotide polymorphisms in the coding region of SCN9A have been associated with increased nociceptor excitability and pain sensitivity. For example, a polymorphism rs6746030 resulting in R1150W substitution in human Nav1.7 has been associated with osteoarthritis pain, lumbar discectomy pain, phantom pain, and pancreatitis pain (Reimann et al., Proc Natl Acad Sci USA 107:5148-53, 2010). DRG neurons expressing the R1150W mutant Nav1.7 display increased firing frequency in response to depolarization (Estacion et al., Ann Neurol 66:862-6, 2009). A disabling form of fibromyalgia has been associated with SCN9A sodium channel polymorphism rs6754031, indicating that some patients with severe fibromyalgia may have a dorsal root ganglia sodium channelopathy (Vargas-Alarcon et al., BMC Musculoskelet Disord 13:23, 2012).

In mice, deletion of the SCN9A gene in nociceptive neurons leads to reduction in mechanical and thermal pain thresholds and reduction or abolition of inflammatory pain responses (Nassar et al., Proc Natl Acad Sci USA 101:12706-11, 2004). Ablating SCN9A in all sensory neurons abolished mechanical pain, inflammatory pain and reflex withdrawal responses to heat. Deleting SCN9A in both sensory and sympathetic neurons abolished mechanical, thermal and neuropathic pain, and recapitulated the pain-free phenotype seen in humans with Nav1.7 loss-of-function mutations (Minett et al., Nat Commun 3:791, 2012). Nav1.7 inhibitors or blockers may therefore be useful in the treatment of a wide range of pain associated with various disorders.

Spider venoms are known to contain a large number of sodium channel blocking peptides, including Huwentoxin-IV (HwTx-IV) (Peng et al., J Biol Chem 277:47564-71, 2002), Protoxin-I, Protoxin-II (Middleton et al., Biochemistry 41:14734-47, 2002) and Phrixotoxin-III (Bosmans et al., Mol Pharmacol 69:419-29, 2006). There is a need for identification of additional Nav1.7 blockers for treatment of a wide range of pain indications. In particular, there is a need for new Nav1.7 blockers with selectivity for Nav1.7 over other voltage gated sodium channel isoforms.

SUMMARY OF THE INVENTION

One embodiment of the invention is an isolated Protoxin-II variant that inhibits human Nav1.7 activity, wherein the Protoxin-II variant has at least one amino acid substitution selected from the group consisting of W7Q and W30L; wherein residue numbering is according to SEQ ID NO: 1.

Another embodiment of the invention is an isolated Protoxin-II variant, wherein the Protoxin-II variant inhibits human Nav1.7 activity with an IC₅₀ value of about 1×10⁻⁷ M or less, about 1×10⁻⁸ M or less, about 1×10⁻⁹ M or less, about 1×10⁻¹⁰ M or less, about 1×10⁻¹¹ M or less, or about 1×10⁻¹² M or less, wherein the IC₅₀ value is measured using a veratridine-induced depolarization inhibition assay using fluorescence resonance energy transfer (FRET) in the presence of 25×10⁻⁶M 3-veratroylveracevine in HEK293 cells stably expressing human Nav1.7, wherein the Protoxin-II variant has a W7Q and/or a W30L substitution, wherein residue numbering is according to SEQ ID NO: 1.

Another embodiment of the invention is an isolated Protoxin-II variant comprising the amino acid sequence of SEQ ID NOs: 30, 40, 44, 52, 56, 56, 59, 65, 78, 109, 110, 111, 114, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 162, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 177, 178, 179, 180, 182, 183, 184, 185, 186, 189, 190, 193, 195, 197, 199, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 224, 226, 227, 231, 232, 243, 244, 245, 247, 249, 252, 255, 258, 261, 263, 264, 265, 266, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 332, 334, 335, 336, 337, 339, 340, 341, 342, 346, 351, 358, 359, 364, 366, 367, 368, 369, 370, 371, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 434, 435, 436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495, 496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 537, 538, 539, 540, 541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555, 556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645, 646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735 or 736.

Another embodiment of the invention is an isolated Protoxin-II variant comprising the amino acid sequence that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 422 (GPYCQKWMQTCDSERKCCEGMVCRLWCKKKLL-COOH); wherein the amino acid sequence has Q at position 7 and L at position 30, when residue numbering is according to SEQ ID NO: 1.

Another embodiment of the invention is an isolated fusion protein comprising the Protoxin-II variant of the invention conjugated to a half-life extending moiety.

Another embodiment of the invention is an isolated polynucleotide encoding the Protoxin-II variant of the invention.

Another embodiment of the invention is a vector comprising the isolated polynucleotide of the invention. Another embodiment of the invention is a host cell comprising the vector of the invention.

Another embodiment of the invention is a method of producing the isolated Protoxin-II variant of the invention, comprising culturing the host cell of the invention and recovering the Protoxin-II variant produced by the host cell.

Another embodiment of the invention is a pharmaceutical composition comprising the isolated Protoxin-II variant or fusion protein of the invention and a pharmaceutically acceptable excipient.

Another embodiment of the invention is a method of treating Nav1.7-mediated pain in a subject, comprising administering to a subject in need thereof an effective amount of the Protoxin-II variant or the fusion protein of the invention to treat the pain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the genus amino acid sequence of Protoxin-II variants that inhibit Nav1.7 with an IC₅₀ value of 30 nM or less in a veratridine-induced depolarization inhibition assay. Residue numbering is according to wild-type Protoxin-II of SEQ ID NO: 1. Genus SEQ ID NO: 403.

FIGS. 2A and 2B show the IC₅₀ values for Nav1.7 and Nav1.6 inhibition in a QPatch assay, and selectivity of each variant calculated by ratio of IC₅₀(Nav1.6)/IC₅₀(Nav1.7) obtained in QPatch assay. SE: standard error. FIG. 2B is a continuation of 2A.

FIGS. 3A, 3B, and 3C show the sequences and the genus sequence of Protoxin-II variants that inhibit Nav1.7 with an IC₅₀ value of 30 nM or less in a FLIPR Tetra assay, and are over 30-fold selective over Nav1.6. Selectivity of each variant was calculated by ratio of IC₅₀(Nav1.6)/IC₅₀9av1.7) obtained in QPatch assay. Residue numbering is according to wild-type Protoxin-II of SEQ ID NO: 1. FIGS. 3B and 3C are continuations of 3A.

FIG. 4A shows efficacy of NV1D3034 (NV1D3034-OH) (SEQ ID NO: 78) against CFA-induced thermal hyperalgesia in mice, assessed by measurement of paw withdrawal latency in the Hargreaves test before (pre-CFA) and after CFA injection (0) and 1-day after peptide administration (1). ***P<0.001 vs. PBS, two-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 4B shows efficacy of NV1D3034 (NV1D3034-OH) (SEQ ID NO: 78) in CFA-induced thermal hyperalgesia in mice, expressed as percent MPE (maximum possible effect) (MPE %) at each dose on day1 following peptide administration. *P<0.05 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 5A shows efficacy of NV1D3368 (NV1D3368-OH) (SEQ ID NO: 198) against CFA-induced thermal hyperalgesia in mice, assessed by measurement of paw withdrawal latency in the Hargreaves test before (pre-CFA) and after CFA injection (0) and 1-day after peptide administration (1). **P<0.01 and ****P<0.0001 vs. PBS, two-way ANOVA followed by Bonferroni's multiple comparison

FIG. 5B shows efficacy of NV1D3368 (NV1D3368-OH) (SEQ ID NO: 198) in CFA-induced thermal hyperalgesia in mice, expressed as percent MPE (MPE %) at each dose on day1 following peptide administration. *P<0.05 and **P<0.01 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 6A shows efficacy of NV1D2775-OH (SEQ ID NO: 56) against CFA-induced thermal hyperalgesia in mice, assessed by measurement of paw withdrawal latency in the Hargreaves test before (pre-CFA) and after CFA injection (0) and 1-day after peptide administration (1). ****P<0.0001 vs. PBS, two-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 6B shows efficacy of NV1D2775-OH (SEQ ID NO: 56) in CFA-induced thermal hyperalgesia in mice, expressed as percent MPE (MPE %) at each dose on day1 following peptide administration. ***P<0.001 and ****P<0.0001 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 6C shows efficacy of NV1D2775-OH (SEQ ID NO: 56) against CFA-induced tactile allodynia in mice. Tactile thresholds of hind paw before (pre-CFA) and after CFA (0) and 1-day after peptide administration (1). ****P<0.0001 vs. PBS, two-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 6D shows efficacy of NV1D2775-OH (SEQ ID NO: 56) against CFA-induced tactile allodynia in mice, expressed as percent MPE (MPE %) on day1 following peptide. ***P<0.001 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 7A shows time course of NV1D2775-OH mediated reversal of thermal hyperalgesia in the mouse CFA model as assessed by measurement of paw withdrawal latency in the Hargreaves test before and after CFA and at various time points post-peptide administration. **P<0.01 vs. PBS, two-way ANOVA followed by Bonferroni's multiple comparison. Shaded areas indicate compound delivery period (0-24 hr).

FIG. 7B shows time course of NV1D2775-OH mediated reversal of tactile allodynia in the mouse CFA model as assessed by measurement of tactile threshold before and after CFA and at various time points post-peptide administration. **P<0.01 vs. PBS, two-way ANOVA followed by Bonferroni's multiple comparison. Shaded areas indicate compound delivery period (0-24 hr).

FIG. 8 shows that NV1D2775-OH produced significant analgesia in the mouse hotplate test. Thermal withdrawal latency was evaluated at 50 and 55° C. pre- and post-pump implantation. Pump implantation had no impact on the latency in the control PBS group. One day after pump, NV1D2775-OH treated-mice exhibited prolonged latency compared to the PBS group. *P<0.05 and ****P<0.0001 vs. PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 9 shows that NV1D2775-OH pretreatment protected animals from carrageenan-induced thermal hyperalgesia in mice. Paw withdrawal latencies were measured pre- and on day1 post-pump before intraplantar carrageenan injection. Latencies were measured again at 2, 3 and 4 hr following carrageenan.

FIG. 10 shows the surface representation of the NMR structure of the wild type Protoxin-II. A hydrophobic face shown on left includes residues W5, M6, W7, L23 and W24. A selectivity face is shown on the right and includes residues S11, E12, K14, E17, G18, L29 and W30. Residue numbering according to SEQ ID NO: 1.

FIG. 11A shows efficacy of the Protoxin-II variant 63955918 SEQ ID NO: 422) after a single intrathecal (IT) administration in the rat tail flick test. Tail withdrawal latency to a thermal stimulus was measured at the indicated time post-peptide administration.

FIG. 11B shows efficacy of the Protoxin-II variant 63955918 SEQ ID NO: 422) in the rat tail flick test expressed as percent area under the curve (AUC %) in the first 120 min after a single intrathecal (IT) administration. ***P<0.001 and ****P<0.0001 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 11C shows efficacy of the Protoxin-II variant 63955918 SEQ ID NO: 422) after a single intrathecal (IT) administration in the rat hot plate test (52.5° C.). The latency of a nociceptive response on a hot plate was measured at the indicated time post-peptide administration.

FIG. 11D shows efficacy of the Protoxin-II variant 63955918 SEQ ID NO: 422) in the hot plate test expressed as percent area under the curve (AUC %) in the first 120 min after a single intrathecal (IT) administration. ***P<0.001 and ****P<0.0001 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 11E shows efficacy of the Protoxin-II variant 63955918 SEQ ID NO: 422) in the rat formalin test. Injection of formalin into the rat hindpaw induced a bi-phasic flinching behavior. Total number of flinches in Phase I (0-10 min post formalin) and Phase II (11-60 min post formalin) was measured by an automated device. No statistics were performed in E) due to small group size.

FIG. 12A shows efficacy of NV1D2775-OH after a single intrathecal (IT) administration in the rat tail flick test. Tail withdrawal latency to a thermal stimulus was measured at the indicated time post-peptide administration.

FIG. 12B shows efficacy of NV1D2775-OH in the rat tail flick test expressed as percent area under the curve (AUC %) in the first 120 min after a single intrathecal (IT) administration. *P<0.05 and **P<0.01 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 12C shows efficacy of NV1D2775-OH after a single intrathecal (IT) administration in the rat hot plate test (52.5° C.). The latency of a nociceptive response on a hot plate was measured at the indicated time post-peptide administration.

FIG. 12D shows efficacy of NV1D2775-OH in the rat hot plate test expressed as percent area under the curve (AUC %) in the first 120 min after a single intrathecal (IT) administration. **P<0.01 and ****P<0.0001 vs PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 12E shows efficacy of NV1D2775-OH in the formalin test. Injection of formalin into the rat hindpaw induced a bi-phasic flinching behavior. Total number of flinches in Phase I (0-10 min post formalin) and Phase II (11-60 min post formalin) was measured by an automated device. **P<0.01 vs PBS, phase I, *P<0.05 vs PBS, phase II, one-way ANOVA followed by Bonferroni's multiple comparison.

FIG. 13A shows efficacy of NV1D3034-OH after a single intrathecal (IT) administration in the rat tail flick test. Tail withdrawal latency to a thermal stimulus was measured at the indicated time post-peptide administration.

FIG. 13B shows efficacy of NV1D3034-OH in the rat tail flick test expressed as percent area under the curve (AUC %) in the first 120 min after a single intrathecal (IT) administration. ***P<0.005 vs PBS, t-test.

FIG. 13C shows efficacy of NV1D3034-OH after a single intrathecal (IT) administration in the rat hot plate test (52.5° C.). The latency of a nociceptive response on a hot plate was measured at the indicated time post-peptide administration.

FIG. 13D shows efficacy of NV1D3034-OH in the rat hot plate test expressed as percent area under the curve (AUC %) in the first 120 min after a single intrathecal (IT) administration. **P<0.01 vs PBS, t-test.

FIG. 13E shows efficacy of NV1D3034-OH in the rat formalin test. Injection of formalin into the rat hindpaw induced a bi-phasic flinching behavior. Total number of flinches in Phase I (0-10 min post formalin) and Phase II (11-60 min post formalin) was measured by an automated device. *P<0.05 vs PBS, phase I, **P<0.01 vs PBS, phase II, t-test.

FIG. 14 shows the amino acid alignment of the Family 3 cysteine knot toxin peptides (SEQ ID NOS 738-740, 1 and 741-755, respectively, in order of appearance).

DETAILED DESCRIPTION OF THE INVENTION

All publications, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference as though fully set forth.

As used herein and in the claims, the singular forms “a,” “and,” and “the” include plural reference unless the context clearly dictates otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which an invention belongs. Although any compositions and methods similar or equivalent to those described herein can be used in the practice or testing of the invention, exemplary compositions and methods are described herein.

The term “polypeptide” means a molecule that comprises at least two amino acid residues linked by a peptide bond to form a polypeptide. Small polypeptides of less than 50 amino acids may be referred to as “peptides”. Polypeptides may also be referred as “proteins”.

The term “polynucleotide” means a molecule comprising a chain of nucleotides covalently linked by a sugar-phosphate backbone or other equivalent covalent chemistry. Double and single-stranded DNAs and RNAs are typical examples of polynucleotides.

The term “complementary sequence” means a second isolated polynucleotide sequence that is antiparallel to a first isolated polynucleotide sequence and that comprises nucleotides complementary to the nucleotides in the first polynucleotide sequence.

The term “vector” means a non-natural polynucleotide capable of being duplicated within a biological system or that can be moved between such systems. Vector polynucleotides typically contain a cDNA encoding a protein of interest and additional elements, such as origins of replication, polyadenylation signal or selection markers, that function to facilitate the duplication or maintenance of these polynucleotides in a biological system. Examples of such biological systems may include a cell, virus, animal, plant, and reconstituted biological systems utilizing biological components capable of duplicating a vector. The polynucleotide comprising a vector may be DNA or RNA molecules or a hybrid of these.

The term “expression vector” means a vector that can be utilized in a biological system or a reconstituted biological system to direct the translation of a polypeptide encoded by a polynucleotide sequence present in the expression vector.

The term “variant” as used herein refers to a polypeptide or a polynucleotide that differs from wild type Protoxin-II polypeptide of SEQ ID NO: 1 or the polynucleotide encoding the wild type Protoxin-II having the sequence of SEQ ID NO: 107 by one or more modifications for example, substitutions, insertions or deletions of nucleotides or amino acids.

Throughout the specification, residues that are substituted in the Protoxin-II variants are numbered corresponding to their position in the wild-type Protoxin-II of SEQ ID NO: 1. For example, “Y1A” in the specification refers to the substitution of tyrosine at residue position that corresponds to the position 1 in the wild type Protoxin-II of SEQ ID NO:1 with alanine.

“Complementary DNA” or “cDNA” refers to a well-known synthetic polynucleotide that shares the arrangement of sequence elements found in native mature mRNA species with contiguous exons, with the intervening introns present in genomic DNA are removed. The codons encoding the initiator methionine may or may not be present in cDNA. cDNA may be synthesized for example by reverse transcription or synthetic gene assembly.

“Synthetic” or “non-natural” as used herein refers to a polynucleotide or a polypeptide molecule not present in nature.

“Nav1.7” (also referred to as hNE or PN1) or “hNav1.7” as used herein refers to the well-known human sodium channel protein type 9 subunit alpha having a sequence shown in GenBank accession number NP 002968.1 and in SEQ ID NO: 79.

The term “wild type Protoxin-II” or “wild type ProTx-II” as used herein refers to the tarantula Thrixopelma pruriens (Peruvian green velvet tarantula) toxin peptide having the amino acid sequence YCQKWMWTCDSERKCCEGMVCRLWCKKKLW-COOH (SEQ ID NO: 1) as described in Middleton et al., Biochemistry 41(50):14734-47, 2002.

The term “recombinant Protoxin-II” or recombinant ProTx-II” as used herein refers to the recombinant Protoxin-II obtained from expression and subsequent cleavage of a Protoxin-II fusion protein having the sequence of GPYCQKWMWTCDSERKCCEGMVCRLWCKKKLW-OH as shown in SEQ ID NO: 2. Recombinant Protoxin-II incorporates a two amino acid N-terminal extension (residues G and P) when compared to the wild type Protoxin-II.

“Blocks human Nav1.7 activity” or “inhibits human Nav1.7 activity” as used herein refers to the ability of the Protoxin-Ill variant of the invention to reduce membrane depolarization induced by veratridine (3-veratroylveracevine) with an IC₅₀ value of about 1×10⁻⁷ M or less in a veratridine-induced depolarization inhibition assay using fluorescence resonance energy transfer (FRET), where veratridine-induced depolarization is measured as a reduction in FRET signal using DISBAC2(3) ([bis-(1,3-diethylthiobarbituric acid) trimethine oxonol]) as an acceptor and PTS18 (trisodium 8-octadecyloxypyrene-1,3,6-trisulfonate) as a donor by exciting the donor at 390-420 nm and measuring FRET at 515-575 nm in a cell line stably expressing human Nav1.7. Ability of the Protoxin-Ill variants of the invention to block human Nav1.7 activity may also be measured using QPatch electrophysiology at single or several Protoxin-Ill variant concentrations according to protocol described in Example 3. The Protoxin-II variant of the invention blocks human Nav1.7 activity when it inhibits Nav1.7 currents measured using QPatch by at least about 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% when using the assay protocol described in Example 3.

“veratridine-induced depolarization inhibition assay” as used herein refers to the assay described in Example 3.

“QPatch assay” or “QPatch electrophysiology assay” as used herein refers to the assay described in Example 3.

The term “substantially identical” as used herein means that the two Protoxin-II variant amino acid sequences being compared are identical or have “insubstantial differences”. Insubstantial differences are substitutions of 1, 2, 3, 4, 5, 6, or 7 amino acids in the Protoxin-II variant amino acid sequence that do not adversely affect peptide properties. Amino acid sequences substantially identical to the Protoxin-II variants disclosed herein are within the scope of the application. In some embodiments, the sequence identity can be about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or higher. Percent identity can be determined for example by pairwise alignment using the default settings of the AlignX module of Vector NTI v.9.0.0 (Invitrogen, Carslbad, Calif.). The protein sequences of the present invention may be used as a query sequence to perform a search against public or patent databases, for example, to identify related sequences. Exemplary programs used to perform such searches are the XBLAST or BLASTP programs (http_//www_ncbi_nlm/nih_gov), or the GenomeQuest™ (GenomeQuest, Westborough, Mass.) suite using the default settings.

Abbreviations of natural amino acids are as used herein are shown in Table 1a.

TABLE 1 Amino acid Three letter code One letter code Alanine Ala A Arginine Arg R Asparagine Asn N Aspartate Asp D Cysteine Cys C Glutamate Glu E Glutamine Gln Q Glycine Gly G Histidine His H Isoleucine Ile I Leucine Leu L Lysine Lys K Methionine Met M Phenylalanine Phe F Proline Pro P Serine Ser S Threonine Thr T Tryptophan Trp W Tyrosine Tyr Y Valine Val V

The present invention provides isolated Protoxin-II (ProTx-II) variant polypeptides that inhibit human Nav1.7 activity, polynucleotides encoding them, vectors, host cells, and methods of using the polynucleotides and polypeptides of the invention. The polypeptides of the invention inhibit depolarization/currents resulting from Nav1.7 activation, and therefore may be useful in the treatment of various conditions associated with pain and conditions associated with sensory or sympathetic neuron dysfunction.

The variants of the invention are potent inhibitors of Nav1.7. The current invention is based, at least in part, on the finding that certain residue substitutions in Protoxin-II enhance selectivity, synthetic yield and/or homogeneity without adversely affecting the potency of the generated Protoxin-II variants, specifically W7 and M19, and additionally residues Y1 and S11, and further additionally residues E12, R22 and (residue numbering according to SEQ ID NO: 1). For example, substitutions at positions W7 and W30 enhance the Protoxin-II variant folding and improve yield. Substitutions at positions S11, E12, K14, E17, G18, L29 and W30 improve selectivity of the resulting Protoxin-II variants to Nav1.7.

One embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-Ill variant, wherein the Protoxin-II variant inhibits human Nav1.7 activity with an IC₅₀ value of about 1×10⁻⁷ M or less, about 1×10⁻⁸ M or less, about 1×10⁻⁹ M or less, about 1×10⁻¹⁰ M or less, about 1×10⁻¹¹ M or less, or about 1×10⁻¹² M or less, wherein the IC₅₀ value is measured using a veratridine-induced depolarization inhibition assay using fluorescence resonance energy transfer (FRET) in the presence of 25×10⁻⁶M 3-veratroylveracevine in HEK293 cells stably expressing human Nav1.7.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant, wherein the Protoxin-II variant inhibits human Nav1.7 activity with an IC₅₀ value of about 1×10⁻⁷ M or less, about 1×10⁻⁸ M or less, about 1×10⁻⁹ M or less, about 1×10⁻¹⁰ M or less, about 1×10⁻¹¹ M or less, or about 1×10⁻¹² M or less, wherein the IC₅₀ value is measured using a veratridine-induced depolarization inhibition assay using fluorescence resonance energy transfer (FRET) in the presence of 25×10⁻⁶ M 3-veratroylveracevine in HEK293 cells stably expressing human Nav1.7, wherein the Protoxin-Ill variant has at least one amino acid substitution selected from the group consisting of W7Q and W30L; wherein residue numbering is according to SEQ ID NO: 1.

Another embodiment of the invention of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant that inhibits human Nav1.7 activity, wherein the Protoxin-II variant has at least one amino acid substitution selected from the group consisting of W7Q and W30L; wherein residue numbering is according to SEQ ID NO: 1.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-II variant has a W7Q substitution.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-II variant has a W30L substitution.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-II variant has a W7Q and a W30L substitution.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-II variant inhibits Nav1.7 activity by at least 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% when the Nav1.7 activity is measured using QPatch assay according to protocol described in Example 3.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-II variant has a substitution at one or more residue positions Y1, W7, S11, E12, K14, E17, G18, R22, L29 and W30, when residue numbering is according to SEQ ID NO: 1.

Substitutions at position Y1 improve potency to human Nav1.7

Substitutions at position W7 improve Protoxin-II variant folding and protein yield.

Substitutions at position S11 improve selectivity to human Nav1.7.

Substitutions at position E12 improve selectivity to human Nav1.7.

Substitutions at position K14 improve selectivity to human Nav1.7.

Substitutions at position E17 improve selectivity to human Nav1.7.

Substitutions at position G18 improve selectivity to human Nav1.7.

Substitutions at position L29 improve selectivity to human Nav1.7.

Substitutions at position W30 improve Protoxin-II variant folding and protein yield and selectivity to Nav1.7.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-Ill variant comprising the sequence YCQKWMQTCDSERKCCEGMVCRLWCKKKLW-COOH (SEQ ID NO: 424); wherein residue Y1, S11, E12, K14, E17, G18, L29 and/or W30 is substituted with any other amino acid shown in Table 1 or a non-natural amino acid, optionally having an N-terminal extension or a C-terminal extension.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the sequence YCQKWMQTCDSERKCCEGMVCRLWCKKKLL-COOH (SEQ ID NO: 425); wherein residue Y1, S11, E12, K14, E17, G18, M19, L29 and/or W30 is substituted with any other amino acid shown in Table 1 or a non-natural amino acid, optionally having an N-terminal extension or a C-terminal extension.

In some embodiments, the Protoxin-II variant of the invention described herein, including in the numbered embodiments listed below, contains at least one a non-natural amino acid.

Non-natural amino acids include amino β-alanine (β-Ala) and other omega-amino acids such as 3-aminopropionic acid (Dap), 2,3-diaminopropionic acid (Dpr), 4-aminobutyric acid and so forth; α-aminoisobutyric acid (Aib); ε-aminohexanoic acid (Aha); δ-aminovaleric acid (Ava); N-methylglycine or sarcosine (MeGly); ornithine (Om); citrulline (Cit); t-butylalanine (t-BuA); t-butylglycine (t-BuG); N-methylisoleucine (MeIle); phenylglycine (Phg); cyclohexylalanine (Cha); norleucine (Nle); 2-naphthylalanine (2-Nal); 4-chlorophenylalanine (Phe(4-Cl)); 2-fluorophenylalanine (Phe(2-F)); 3-fluorophenylalanine (Phe(3-F)); 4-fluorophenylalanine (Phe(4-F)); penicillamine (Pen); 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic); α-2-thienylalanine (Thi); methionine sulfoxide (MSO); N(omega)-methyl-L-arginine; N(omega), N(omega)-dimethyl-L-arginine (asymmetrical); 4-guanidino-L-phenylalanine; L-Lys(N-epsilon-(N-alpha-Palmitoyl-L-gamma-glutamyl); L-asparagyl-4-aminobutane; L-glutamyl-4-aminobutane; homoarginine (hArg); N-acetyl lysine (AcLys); 2,3-diaminobutyric acid (Dab); 2,4-diaminobutyric acid (Dbu); p-aminophenylalanine (Phe(pNH₂)); N-methyl valine (MeVal); homocysteine (hCys) and homoserine (hSer); 4-bromophenylalanine (Phe(4-Br); 5-bromotryphophan (Trp(5-Br)); 3-chlorotyrosine (Tyr(3-Cl)) or beta-chloroalanine.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the sequence

-   -   X₁X₂X₃CX₄X₅WX₆QX₇CX₈X₉X₁₀X₁₁X₁₂CCX₁₃X₁₄X₁₅X₁₆CX₁₇LWCX₁₈KKLX₁₉         (SEQ ID NO: 432),         -   X₁ is G, P, A or deleted;         -   X₂ is P, A or deleted;         -   X₃ is S, Q, A, R or Y;         -   X₄ is Q, R, K, A, S or Y;         -   X₅ is K, S, Q or R;         -   X₆ is M or F;         -   X₇ is T, S, R, K or Q;         -   X₈ is D, T, or asparagyl-4-aminobutane;         -   X₉ is S, A, R, I or V;         -   X₁₀ is E, R, N, K, T, Q, Y or glutamyl-4-aminobutane;         -   X₁₁ is R or K;         -   X₁₂ is K, Q, S, A or F;         -   X₁₃ is E, Q, D, L, N, or glutamyl-4-aminobutane;         -   X₁₄ is G, Q or P;         -   X₁₅ is M or F;         -   X₁₆ is V or S;         -   X₁₇ is R, T or N-omega methyl-L-arginine; and         -   X₁₈ is K or R; and         -   X₁₉ is W or L,         -   optionally having an N-terminal extension or a C-terminal             extension.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the sequence X₁X₂X₃CQKWMQTCDX₄X₅RX₆CCX₇X₈X₉VCRLWCKKKX₁₀X₁₁ (SEQ ID NO: 737); wherein

X₁ is G, P, A or deleted;

X₂ is P, A or deleted;

X₃ is S, Q, A, R or Y;

X₄ is S, A, R, I or V;

X₅ is E, R, N, K, T, Q, Y or glutamyl-4-aminobutane;

X₆ is K, Q, S, A or F;

X₇ is E, Q, D, L, N or glutamyl-4-aminobutane;

X₈ is G, Q or P;

X₉ is M or F;

X₁₀ is L, V; and

X₁₁ is W or L.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-Ill variant inhibits human Nav1.7 activity with an IC₅₀ value of about 1×10⁻⁷ M or less, wherein the IC₅₀ value is measured using a veratridine-induced depolarization inhibition assay using fluorescence resonance energy transfer (FRET) in the presence of 25×10⁻⁶ M 3-veratroylveracevine in HEK293 cells stably expressing human Nav1.7.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-II variant inhibits Nav1.7 activity by at least 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% when the Nav1.7 activity is measured using QPatch assay according to protocol described in Example 3.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the N-terminal extension comprises the amino acid sequences of SEQ ID NOs: 372, 373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384 or 385.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the C-terminal extension comprises the amino acid sequence of SEQ ID NOs: 374, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396 or 397.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the N-terminal and/or the C-terminal extension is conjugated to the Protoxin-II variant via a linker.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the linker comprises the amino acid sequence of SEQ ID NOs: 383, 392, 398, 399, 400, 401 or 402.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the N-terminal extension consists of the amino acid sequences of SEQ ID NOs: 372, 373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384 or 385.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the C-terminal extension consists of the amino acid sequence of SEQ ID NOs: 374, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396 or 397.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the linker consists of the amino acid sequence of SEQ ID NOs: 383, 392, 398, 399, 400, 401 or 402.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the sequence

-   -   X₁X₂X₃CX₄X₅WX₆QX₇CX₈X₉X₁₀X₁₁X₁₂CCX₁₃X₁₄FX₁₅CX₁₆LWCX₁₇KKL W (SEQ         ID NO: 403), wherein         -   X₁ is G, P, A or deleted;         -   X₂ is P, A or deleted;         -   X₃ is S, Q, A, R or Y;         -   X₄ is Q, R, K, A or S;         -   X₅ is K, S, Q or R;         -   X₆ is M or F;         -   X₇ is T, S, R, K or Q;         -   X₈ is D or T;         -   X₉ is S, A or R;         -   X₁₀ is E, R, N, K, T or Q;         -   X₁₁ is R or K;         -   X₁₂ is K, Q, S or A;         -   X₁₃ is E, Q or D;         -   X₁₄ is G or Q;         -   X₁₅ is V or S;         -   X₁₆ is R or T; and         -   X₁₇ is K or R;         -   optionally having an N-terminal extension or a C-terminal             extension,         -   wherein the polypeptide inhibits human Nav1.7 activity with             an IC₅₀ value of about 1×10⁻⁷ M or less, wherein the IC₅₀             value is measured using a veratridine-induced depolarization             inhibition assay using fluorescence resonance energy             transfer (FRET) in the presence of 25×10⁻⁶ M             3-veratroylveracevine in HEK293 cells stably expressing             human Nav1.7.

The Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below are potent Nav1.7 inhibitors. Recombinant Protoxin-II (SEQ ID NO: 2) has an IC₅₀ value of about 4×10⁻⁹ M for human Nav1.7 in a veratridine-induced depolarization inhibition assay measuring decline in FRET (fluorescence resonance energy transfer) in cells stably expressing Nav1.7 using FLIPR® Tetra instrument (Molecular Devices) using experimental details described in Example 3. A Protoxin-II variant is “a potent” Nav1.7 inhibitor when the IC₅₀ value in the assay described above and in Experiment 3 is about 30×10⁻⁹ M or less i.e. within 10 fold of recombinant Protoxin-II. For clarity, an IC₅₀ of 30×10⁻⁹ M is identical to IC₅₀ of 3.0×10⁻⁸ M.

The Protoxin-II variant polypeptides of the invention disclosed herein, including in the numbered embodiments listed below may be produced by chemical synthesis, such as solid phase peptide synthesis, on an automated peptide synthesizer. Alternatively, the polypeptides of the invention may be obtained from polynucleotides encoding the polypeptides by the use of cell-free expression systems such as reticulocyte lysate based expression systems, or by recombinant expression systems. Those skilled in the art will recognize other techniques for obtaining the polypeptides of the invention. In an exemplary method, the Protoxin-II variants of the invention are generated by expressing them as human serum albumin (HSA) fusion proteins utilizing a glycine-rich linker such as (GGGGS)₄ (SEQ ID NO:80) or (GGGGS)₆ (SEQ ID NO: 81) coupled to a protease cleavable linker such as a recognition sequence for HRV3C protease (Recombinant type 14 3C protease from human rhinovirus) LEVLFQGP (HRV3C linker) (SEQ ID NO: 82), and cleaving the expressed fusion proteins with the HRV3C protease to release the recombinant Protoxin-II variant peptides. Hexahistidine (SEQ ID NO: 108) or other tags may be used to facilitate purification using well known methods.

Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be purified using methods described herein. In an exemplary method, Protoxin-II variants of the invention expressed as HSA fusion proteins and cleaved with HRV3C protease may be purified using sold phase extraction (SPE) as described herein.

Generation of the Protoxin-II variants disclosed herein, including in the numbered embodiments listed below optionally having N-terminal and/or C-terminal extensions, and Protoxin-II variant fusion proteins is typically achieved at the nucleic acid level. The polynucleotides may be synthesized using chemical gene synthesis according to methods described in U.S. Pat. Nos. 6,521,427 and 6,670,127, utilizing degenerate oligonucleotides to generate the desired variants, or by standard PCR cloning and mutagenesis. Libraries of variants may be generated by standard cloning techniques to clone the polynucleotides encoding the Protoxin-II variants into the vector for expression.

The Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may incorporate additional N- and/or C-terminal amino acids when compared to the wild type Protoxin-II of SEQ ID NO: 1, for example resulting from cloning and/or expression schemes. For example, cleavage from HSA after expression of the variant as HSA-linker-HRV3C cleavable peptide-Protoxin-II variant fusion protein may result in the incorporation of additional two residues to the N-terminus of each Protoxin-II variant, such as G and P.

The Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below are tested for their ability to inhibit human Nav1.7 using methods described herein. An exemplary assay is a veratridine-induced depolarization inhibition assay measuring decline in FRET (fluorescence resonance energy transfer) in cells stably expressing Nav1.7. Another exemplary assay employs electrophysiological recordings to measure changes in Nav1.7-mediated currents using well known patch clamp techniques and as described herein.

Another embodiment of the invention is an isolated Protoxin-II variant disclosed herein, including in the numbered embodiments listed below comprising the amino acid sequence of SEQ ID NOs: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 35, 357, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368 369, 370, 371, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 434, 435, 436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495, 496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 537, 538, 539, 540, 541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555, 556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645, 646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735 or 736.

The Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may inhibit human Nav1.7 with an IC₅₀ value of about 1×10⁻⁷ M or less, about 1×10⁻⁸ M about 1×10⁻⁹ or less, about 1×10⁻¹⁰ M or less, about 1×10⁻¹¹ M or less, or about 1×10⁻¹² M or less. Exemplary variants demonstrating the range of IC₅₀ values are variants having amino acid sequences shown in SEQ ID NOs: 30, 40, 44, 52, 56, 56, 59, 65, 78, 109, 110, 111, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 162, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 177, 178, 179, 180, 182, 183, 184, 185, 186, 189, 190, 193, 195, 197, 199, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 224, 226, 227, 231, 232, 243, 244, 245, 247, 249, 252, 255, 258, 261, 263, 264, 265, 266, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 332, 334, 335, 336, 337, 339, 340, 341, 342, 346, 351, 358, 359, 364, 366, 367, 368, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430 or 431.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the Protoxin-II variant inhibits Nav1.7 activity by at least 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% when the Nav1.7 activity is measured using QPatch assay according to protocol described in Example 3. Exemplary variants inhibiting Nav1.7 activity by at least 25% in a QPatch assay are variants having amino acid sequences shown in SEQ ID NOs: 109, 133, 408, 409, 410, 412, 419, 420, 421, 422, 423, 423, 424, 425, 426, 427, 427, 428, 429, 430, 431, 431, 434, 436, 437, 438, 439, 440, 441, 442, 444, 446, 447, 448, 450, 452, 453, 455, 456, 459, 460, 461, 462, 463, 464, 465, 466, 468, 469, 470, 471, 473, 474, 476, 477, 478, 479, 480, 482, 483, 485, 486, 487, 490, 491, 492, 494, 495, 496, 497, 498, 499, 500, 502, 504, 505, 507, 508, 510, 511, 512, 514, 516, 517, 518, 519, 521, 522, 523, 524, 526, 529, 531, 532, 533, 537, 546, 554, 557, 559, 560, 561, 562, 563, 566, 571, 579, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 621, 622, 632, 633, 634, 635, 636, 637, 638, 639, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684 and 685.

Table 2, Table 3, Table 14, Table 18 and Table 2 show the sequences of select Protoxin-II variants.

TABLE 2 Protoxin-II  variant SEQ Protein peptide ID name name NO: Protein amino acid sequence wild type  1 YCQKWMWTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D12  2 GPYCQKWMWTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D748  3 GPACQKWMWTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D751  4 GPQCQKWMWTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D2292  5 GPRCQKWMWTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D750  6 GPSCQKWMWTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D1328  7 GPYCQKWFWTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D774  8 GPYCQKWMQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D786  9 GPYCQKWMWTCDAERKCCEGMVCRLWCKKKLW-COOH NV1D2300 10 GPYCQKWMWTCDRERKCCEGMVCRLWCKKKLW-COOH NV1D791 11 GPYCQKWMWTCDSKRKCCEGMVCRLWCKKKLW-COOH NV1D1332 12 GPYCQKWMWTCDSNRKCCEGMVCRLWCKKKLW-COOH NV1D2512 13 GPYCQKWMWTCDSERKCCEGFVCRLWCKKKLW-COOH NV1D1336 14 GPYCQKWMWTCDSERKCCEGLVCRLWCKKKLW-COOH NV1D1337 15 GPYCQKWMWTCDSERKCCEGMVCTLWCKKKLW-COOH NV1D2308 16 GPYCQKWMWTCDSERKCCEGMVCRLWCRKKLW-COOH NV1G953 NV1D2670 17 GPACQKWMQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1G951 NV1D2674 18 GPACQKWMWTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G909 NV1D2664 19 GPACQKWMWTCDSERKCCEGFVCRLWCKKKLW-COOH NV1G963 NV1D2671 20 GPQCQKWMQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1G949 NV1D2675 21 GPQCQKWMWTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G977 NV1D2665 22 GPQCQKWMWTCDSERKCCEGFVCRLWCKKKLW-COOH NV1G957 NV1D2668 23 GPRCQKWMQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1G965 NV1D2672 24 GPRCQKWMWTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G973 NV1D2662 25 GPRCQKWMWTCDSERKCCEGFVCRLWCKKKLW-COOH NV1G975 NV1D2669 26 GPSCQKWMQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1G971 NV1D2673 27 GPSCQKWMWTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G995 NV1D2663 28 GPSCQKWMWTCDSERKCCEGFVCRLWCKKKLW-COOH NV1G961 NV1D2676 29 GPYCQKWMQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G911 NV1D2666 30 GPYCQKWMQTCDSERKCCEGFVCRLWCKKKLW-COOH NV1D2816 31 GPACQKWFQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1G905 NV1D2735 32 GPACQKWMQTCDSERKCCEGFVCRLWCKKKLW-COOH NV1G919 NV1D2739 33 GPACQKWMWTCDAERKCCEGFVCRLWCKKKLW-COOH NV1G979 NV1D2731 34 GPACQKWMQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1D2810 35 GPQCQKWFQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1G1099 NV1D2732 36 GPQCQKWMQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G1011 NV1D2740 37 GPQCQKWMWTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2819 38 GPRCQKWFWTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G1105 NV1D2729 39 GPRCQKWMQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G1013 NV1D2733 40 GPRCQKWMQTCDSERKCCEGFVCRLWCKKKLW-COOH NV1D2814 41 GPSCQKWFQTCDSERKCCEGMVCRLWCKKKLW-COOH NV1D2820 42 GPSCQKWFWTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G983 NV1D2730 43 GPSCQKWMQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G1003 NV1D2734 44 GPSCQKWMQTCDSERKCCEGFVCRLWCKKKLW-COOH NV1G1009 NV1D2738 45 GPSCQKWMWTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2851 46 GPYCQKWFKTCDAERKCCEGMVCRLWCKKKLW-COOH NV1D2850 47 GPYCQKWFQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1G987 NV1D2667 48 GPYCQKWMWTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2867 49 GPACQKWFQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1D2881 50 GPACQKWFQTCDSERKCCEGFVCRLWCKKKLW-COOH NV1D2882 51 GPACQKWFQTCDSERKCCEGLVCRLWCKKKLW-COOH NV1G899 NV1D2774 52 GPACQKWMQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1G1077 NV1D2902 53 GPACQKWMQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2861 54 GPQCQKWFQTCDAERKCCEGMVCRLWCKKKLW-COOH NV1D2870 55 GPQCQKWFQTCDSERKCCEGLVCRLWCKKKLW-COOH NV1G1007 NV1D2775 56 GPQCQKWMQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1G1067 NV1D2893 57 GPQCQKWMQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2887 58 GPRCQKWFWTCDAERKCCEGFVCRLWCKKKLW-COOH NV1G1005 NV1D2772 59 GPRCQKWMQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1G1061 NV1D2896 60 GPRCQKWMQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2877 61 GPSCQKWFQTCDSERKCCEGFVCRLWCKKKLW-COOH NV1D2878 62 GPSCQKWFQTCDSERKCCEGLVCRLWCKKKLW-COOH NV1D2889 63 GPSCQKWFWTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2889 64 GPSCQKWFWTCDAERKCCEGFVCRLWCKKKLW-COOH NV1G1001 NV1D2773 65 GPSCQKWMQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2890 66 GPSCQKWFWTCDAERKCCEGLVCRLWCKKKLW-COOH NV1G1109 NV1D2899 67 GPSCQKWMQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2905 68 GPYCQKWFQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2906 69 GPYCQKWFQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2921 70 GPACQKWFQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2922 71 GPACQKWFQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2909 72 GPQCQKWFQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2910 73 GPQCQKWFQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2913 74 GPRCQKWFQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2914 75 GPRCQKWFQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1D2917 76 GPSCQKWFQTCDAERKCCEGFVCRLWCKKKLW-COOH NV1D2918 77 GPSCQKWFQTCDAERKCCEGLVCRLWCKKKLW-COOH NV1G1153 NV1D3034 78 GPQCQKWMQTCDRERKCCEGFVCTLWCRKKLW-COOH

TABLE 3  Protoxin-II variant SEQ ID Protein name peptide name NO: Protein amino acid sequence (-GP) NV1G1001 (-GP) NV1D2773 109 SCQKWMQTCDAERKCCEGFVCRLW CKKKLW-COOH (-GP) NV1G1001- (-GP) NV1D2773- 110 SCQKWMQTCDAERKCCEGFVCRLW NH-Me NH2 CKKKLW-NH2 NV1G1007-NH2 NV1D2775-NH2 111 GPQCQKWMQTCDAERKCCEGFVCR LWCKKKLW-NH2 NV1G1107-NH2 NV1D2890-NH2 112 GPSCQKWFWTCDAERKCCEGLVCRL WCKKKLW-NH2 NV1G1137 NV1D2974 113 GPQCQKWMQTCDAERKCCEGFSCT LWCKKKLW-COOH (-GP) N-Ac- (-GP) N-Ac- 114 Ac- NV1G1137-NH2 NV1D2974-NH2 QCQKWMQTCDAERKCCEGFSCTLW CKKKLW-NH2 (-GP) N-Ac- (-GP) N-Ac- 115 Ac- NV1G1137- NV1D2974 QCQKWMQTCDAERKCCEGFSCTLW CKKKLW-COOH NV1G1153 NV1D3034 116 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1153-NH2 NV1D3034-NH2 117 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLW-NH2 NV1G1153-NH- NV1D3034-NH- 118 GPQCQKWMQTCDRERKCCEGFVCT butyl butyl LWCRKKLW-NH-butyl NV1G1153-NH- NV1D3034-NH- 119 GPQCQKWMQTCDRERKCCEGFVCT methyl methyl LWCRKKLW-NH-methyl (-GP) N-Ac- (-GP) N-Ac- 120 Ac- NV1G1153 NV1D3034 QCQKWMQTCDRERKCCEGFVCTLW CRKKLW-COOH (-GP) N-Ac- (-GP) N-Ac- 121 Ac- NV1G1153-NH2 NV1D3034-NH2 QCQKWMQTCDRERKCCEGFVCTLW CRKKLW-NH2 NV1G1818 NV1D3368 122 GPQCQKWMQTCDRTRKCCEGFVCT LWCRKKLW-COOH NV1G1818-NH2 NV1D3368-NH2 123 GPQCQKWMQTCDRTRKCCEGFVCT LWCRKKLW-NH2 NV1G1147 NV1D2969 124 GPSCQKWMQTCDAERKCCEGFSCRL WCKKKLW-COOH NV1G1145 NV1D2970 125 GPSCQKWMQTCDAERKCCEGFVCT LWCKKKLW-COOH NV1G1143 NV1D2971 126 GPSCQKWMQTCDAERKCCEGFSCTL WCKKKLW-COOH NV1G1141 NV1D2972 127 GPQCQKWMQTCDAERKCCEGFSCR LWCKKKLW-COOH NV1G1139 NV1D2973 128 GPQCQKWMQTCDAERKCCEGFVCT  LWCKKKLW-COOH NV1G1137 NV1D2974 129 GPQCQKVVMQTCDAERKCCEGFSCT  LWCKKKLW-COOH NV1G1137-NH2 NV1D2974-NH2 130 GPQCQKWMQTCDAERKCCEGFSCT  LWCKKKLW-NH2 NV1G1517 NV1D3004 131 GPQCQKWMQTCDRERKCCEGFVCR  LWCKKKLW-COOH NV1G1515 NV1D3005 132 GPQCQKWMQTCDANRKCCEGFVC  RLWCKKKLW-COOH NV1G1519 NV1D3006 133 GPQCQKWMQTCDARRKCCEGFVCR  LWCKKKLW-COOH NV1G1513 NV1D3007 134 GPQCQKWMQTCDAERKCCEGFVCR  LWCRKKLW-COOH NV1G1523 NV1D3012 135 GPQCQKWMQTCDRNRKCCEGFVC  RLWCKKKLW-COOH NV1G1525 NV1D3013 136 GPQCQKWMQTCDRRRKCCEGFVCR  LWCKKKLW-COOH NV1G1255 NV1D3014 137 GPQCQKWMQTCDRERKCCEGFVCT  LWCKKKLW-COOH NV1G1187 NV1D3015 138 GPQCQKWMQTCDRERKCCEGFVCR  LWCRKKLW-COOH NV1G1257 NV1D3016 139 GPQCQKWMQTCDANRKCCEGFVCT  LWCKKKLW-COOH NV1G1221 NV1D3017 140 GPQCQKWMQTCDARRKCCEGFVCT  LWCKKKLW-COOH NV1G1521 NV1D3018 141 GPQCQKWMQTCDANRKCCEGFVC RLWCRKKLW-COOH NV1G1531 NV1D3019 142 GPQCQKWMQTCDARRKCCEGFVCR  LWCRKKLW-COOH NV1G1239 NV1D3020 143 GPQCQKWMQTCDAERKCCEGFVCT  LWCRKKLW-COOH NV1G1583 NV1D3030 144 GPQCQKWMQTCDRNRKCCEGFVCT  LWCKKKLW-COOH NV1G1527 NV1D3031 145 GPQCQKWMQTCDRRRKCCEGFVCT  LWCKKKLW-COOH NV1G1511 NV1D3032 146 GPQCQKWMQTCDRNRKCCEGFVC  RLWCRKKLW-COOH NV1G1509 NV1D3033 147 GPQCQKWMQTCDRRRKCCEGFVCR  LWCRKKLW-COOH NV1G1231 NV1D3035 148 GPQCQKWMQTCDANRKCCEGFVCT  LWCRKKLW-COOH NV1G1211 NV1D3036 149 GPQCQKWMQTCDARRKCCEGFVCT  LWCRKKLW-COOH NV1G1267 NV1D3044 150 GPQCQKWMQTCDRNRKCCEGFVCT  LWCRKKLW-COOH NV1G1269 NV1D3045 151 GPQCQKWMQTCDRRRKCCEGFVCT  LWCRKKLW-COOH NV1G1215 NV1D3048 152 GPQCQKWMQTCDAKRKCCEGFVCR LWCKKKLW-COOH NV1G1593 NV1D3050 153 GPQCQKWMQTCDRKRKCCEGFVCR LWCKKKLW-COOH NV1G1263 NV1D3051 154 GPQCQKWMQTCDAKRKCCEGFVCT LWCKKKLW-COOH NV1G1585 NV1D3052 155 GPQCQKWMQTCDAKRKCCEGFVCR LWCRKKLW-COOH NV1G1623 NV1D3056 156 GPQCQKWMQTCDRKRKCCEGFVCT LWCKKKLW-COOH NV1G1613 NV1D3057 157 GPQCQKWMQTCDRKRKCCEGFVCR LWCRKKLW-COOH NV1G1259 NV1D3058 158 GPQCQKWMQTCDAKRKCCEGFVCT LWCRKKLW-COOH NV1G1265 NV1D3062 159 GPQCQKWMQTCDRKRKCCEGFVCT LWCRKKLW-COOH NV1G1273 NV1D3109 160 GPQCQKWMWTCDARRKCCEGFVC TLWCRKKLW-COOH NV1G1225 NV1D3121 161 GPQCQKWMWTCDRKRKCCEGFVC TLWCRKKLW-COOH NV1G1886 NV1D3249 162 GPAAAAAQCQKWMQTCDAERKCC EGFVCRLWCKKKLW-COOH NV1G1633 NV1D3251 163 GPAPAPAQCQKWMQTCDAERKCCE GFVCRLWCKKKLW-COOH NV1G1631 NV1D3252 164 GPQCQKWMQTCDAERKCCEGFVCR LWCKKKLWAPAPA-COOH NV1G1885 NV1D3254 165 GPQCQKWMQTCDAERKCCEGFVCR LWCKKKLWGGGGG-COOH NV1G1884 NV1D3256 166 GPCCNCSSKWCRDHSRCCGRGSAPA PAPAPAPGSQCQKWMQTCDAERKC CEGFVCRLWCKKKLW-COOH NV1G1881 NV1D3257 167 GPQCQKWMQTCDAERKCCEGFVCR LWCKKKLWGSAPAPAPAPAPGSCCN CSSKWCRDHSRCC-COOH NV1G1879 NV1D3259 168 GPQCQKWMQTCDAERKCCEGFVCR LWCKKKLWGSAPAPAPAPAPAPAPA PAPAPGSCCNCSSKWCRDHSRCCGR- COOH NV1G1883 NV1D3260 169 GPCCNCSSKWCRDHSRCCGRGSAPA PAPAPAPAPAPAPAPAPGSQCQKW MQTCDAERKCCEGFVCRLWCKKKLW- COOH NV1G1880 NV1D3261 170 GPQCQKWMQTCDAERKCCEGFVCR LWCKKKLWGSAPAPAPAPAPAPAPA PAPAPGSCCNCSSKWCRDHSRCC- COOH NV1G1882 NV1D3262 171 GPCCNCSSKWCRDHSRCCGSAPAPA PAPAPAPAPAPAPAPGSQCQKWMQ TCDAERKCCEGFVCRLWCKKKLW- COOH NV1G1776 NV1D3339 172 GPQCRKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1775 NV1D3340 173 GPQCKKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1768 NV1D3341 174 GPQCTKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1777 NV1D3342 175 GPQCAKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1770 NV1D3344 176 GPQCEKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1767 NV1D3345 177 GPQCSKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1769 NV1D3346 178  GPQCQRWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1774 NV1D3347 179 GPQCQTWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1771 NV1D3348 180 GPQCQAWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1778 NV1D3349 181 GPQCQDWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1773 NV1D3350 182 GPQCQEWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1779 NV1D3351 183 GPQCQQWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1772 NV1D3352 184 GPQCQSWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1868 NV1D3353 185 GPQCQKWMQRCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1824 NV1D3354 186 GPQCQKWMQKCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1863 NV1D3356 187 GPQCQKWMQDCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1826 NV1D3357 188 GPQCQKWMQECDRERKCCEGFVCT LWCRKKLW-COOH NV1G1810 NV1D3358 189 GPQCQKWMQQCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1836 NV1D3359 190 GPQCQKWMQSCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1834 NV1D3360 191 GPQCQKWMQTCRRERKCCEGFVCT LWCRKKLW-COOH NV1G1829 NV1D3361 192 GPQCQKWMQTCKRERKCCEGFVCT LWCRKKLW-COOH NV1G1820 NV1D3362 193 GPQCQKWMQTCTRERKCCEGFVCT LWCRKKLW-COOH NV1G1828 NV1D3363 194 GPQCQKWMQTCARERKCCEGFVCT LWCRKKLW-COOH NV1G1827 NV1D3365 195 GPQCQKWMQTCQRERKCCEGFVCT LWCRKKLW-COOH NV1G1857 NV1D3366 196 GPQCQKWMQTCSRERKCCEGFVCT LWCRKKLW-COOH NV1G1823 NV1D3367 197 GPQCQKWMQTCDRQRKCCEGFVCT  LWCRKKLW-COOH NV1G1818 NV1D3368 198 GPQCQKWMQTCDRTRKCCEGFVCT  LWCRKKLW-COOH NV1G1811 NV1D3369 199 GPQCQKWMQTCDREKKCCEGFVCT  LWCRKKLW-COOH NV1G1853 NV1D3370 200 GPQCQKWMQTCDRETKCCEGFVCT  LWCRKKLW-COOH NV1G1817 NV1D3371 201 GPQCQKWMQTCDREAKCCEGFVCT  LWCRKKLW-COOH NV1G1814 NV1D3372 202 GPQCQKWMQTCDREDKCCEGFVCT  LWCRKKLW-COOH NV1G1831 NV1D3374 203 GPQCQKWMQTCDREQKCCEGFVCT  LWCRKKLW-COOH NV1G1819 NV1D3375 204 GPQCQKWMQTCDRESKCCEGFVCT  LWCRKKLW-COOH NV1G1859 NV1D3376 205 GPQCQKWMQTCDRERRCCEGFVCT  LWCRKKLW-COOH NV1G1825 NV1D3377 206 GPQCQKWMQTCDRERTCCEGFVCT  LWCRKKLW-COOH NV1G1821 NV1D3378 207 GPQCQKWMQTCDRERACCEGFVCT  LWCRKKLW-COOH NV1G1835 NV1D3379 208 GPQCQDWMQTCDRERDCCLGFVCT  LWCRKKLW-COOH NV1G1815 NV1D3380 209 GPQCQEWMQTCDRERECCEGFVCT  LWCRKKLW-COOH NV1G1833 NV1D3381 210 GPQCQKWMQTCDRERQCCEGFVCT  LWCRKKLW-COOH NV1G1812 NV1D3382 211 GPQCQKWMQTCDRERSCCEGFVCT  LWCRKKLW-COOH NV1G1782 NV1D3383 212 GPQCQKWMQTCDRERKCCRGFVCT  LWCRKKLW-COOH NV1G1783 NV1D3384 213 GPQCQKWMQTCDRERKCCKGFVCT  LWCRKKLW-COOH NV1G1785 NV1D3385 214 GPQCQKWMQTCDRERKCCTGFVCT  LWCRKKLW-COOH NV1G1784 NV1D3386 215 GPQCQKWMQTCDRERKCCAGFVCT  LWCRKKLW-COOH NV1G1780 NV1D3387 216 GPQCQKWMQTCDRERKCCDGFVCT  LWCRKKLW-COOH NV1G1781 NV1D3388 217 GPQCQKWMQTCDRERKCCQGFVCT  LWCRKKLW-COOH NV1G1786 NV1D3389 218 GPQCQKWMQTCDRERKCCSGFVCT  LWCRKKLW-COOH MV1G1851 NV1D3390 219 GPQCQKWMQTCDREKRCCERFVCT LWCRKKLW-COOH NV1G1852 NV1D3391 220 GPQCQKWMQTCDRERKCCEKFVCT  LWCRKKLW-COOH NV1G1854 NV1D3392 221 GPQCQKWMQTCDRERKCCETFVCT  LWCRKKLW-COOH NV1G1860 NV1D3393 222 GPQCQKWMQTCDRERKCCEAFVCT  LWCRKKLW-COOH NV1G1789 NV1D3394 223 GPQCQKWMQTCDRERKCCEDFVCT  LWCRKKLW-COOH NV1G1787 NV1D3396 224 GPQCQKWMQTCDRERKCCEQFVCT  LWCRKKLW-COOH NV1G1856 NV1D3397 225 GPQCQKWMQTCDRERKCCESFVCT  LWCRKKLW-COOH NV1G1855 NV1D3398 226 GPQCQKWMQTCDRERKCCEGFSCT  LWCRKKLW-COOH NV1G1788 NV1D3399 227 GPQCQKWMQTCDRERKCCEGFTCT  LWCRKKLW-COOH NV1G1849 NV1D3400 228 GPQCQKWMQTCDRERKCCEGFQCT  LWCRKKLW-COOH NV1G1795 NV1D3401 229 GPQCQKWMQTCDRERKCCEGFVCT  LWCRRKLW-COOH NV1G1803 NV1D3403 230 GPQCQKWMQTCDRERKCCEGFVCT  LWCRAKLW-COOH NV1G1807 NV1D3408 231 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKRLW-COOH MV1G1806 NV1D3409 232 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKTLW-COOH NV1G1805 NV1D3410 233 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKALW-COOH NV1G1809 NV1D3413 234 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKQLW-COOH NV1G1850 NV1D3414 235 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKSLW-COOH NV1G1793 NV1D3419 236 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLD-COOH NV1G1822 NV1D3423 237 GPQCQKWMQTCRRRRKCCEGFVCT  LWCRKKLW-COOH NV1G1813 NV1D3424 238 GPQCQKWMQTCKRKRKCCEGFVCT  LWCRKKLW-COOH NV1G1840 NV1D3425 239 GPQCQKWMQTCRRRDKCCEGFVCT  LWCRKKLW-COOH NV1G1848 NV1D3426 240 GPQCQKWMQTCKRKDKCCEGFVCT  LWCRKKLW-COOH NV1G1841 NV1D3427 241 GPQCQKWMQTCRRREKCCEGFVCT  LWCRKKLW-COOH NV1G1844 NV1D3428 242 GPQCQKWMQTCKRKEKCCEGFVCT  LWCRKKLW-COOH MV1G1842 NV1D3430 243 GPQCQDWMQTCDRERKCCKGFVCT LWCRKKLW-COOH NV1G1846 NV1D3431 244 GPQCQEWMQTCDRERKCCKGFVCT  LWCRKKLW-COOH NV1G1843 NV1D3432 245 GPQCQEWMQTCDRERKCCRGFVCT  LWCRKKLW-COOH NV1G1892 NV1D3439 24b GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLG-COOH NV1G1916 NV1D3465 247 GPQCQKFMQTCDRERKCCEGFVCTL  WCRKKLW-COOH NV1G1922 NV1D3466 248 GPQCQKWMQTCDEERKCCEGFVCT  LWCRKKLW-COOH NV1G1915 NV1D3467 249 GPQCQKWMQTCDRERKCCGGFVCT  LWCRKKLW-COOH NV1G1924 NV1D3470 250 GPQCQKWMQTCDRERKCCEGLVCT  LWCRKKLW-COOH NV1G1709 NV1D3510 251 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPASPGARAF-COOH NV1G1681 NV1D3511 252 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWSPGARAF-COOH NV1G1693 NV1D3512 253 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPAPAPAPDGPWRKM- COOH NV1G1705 NV1D3513 254 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPADGPWRKM-COOH NV1G1689 NV1D3514 255 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWDGPWRKM-COOH NV1G1711 NV1D3515 256 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPAPAPAPFGQKASS- COOH NV1G1685 NV1D3516 257 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPAFGQKASS-COOH NV1G1697 NV1D3517 258 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWFGQKASS-COOH NV1G1695 NV1D3518 259 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPAPAPAPQRFVTG  HFGGLYPANG-COOH NV1G1701 NV1D3519 260 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPAQRFVTGHFGGLY  PANG-COOH NV1G1691 NV1D3520 261 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWQRFVTG  HFGGLYPANG-COOH NV1G1679 NV1D3521 262 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWAPAPAPAPAPRRRRRRR  RRRR-COOH NV1G1683 NV1D3523 263 GPQCQKWMQTCDRERKCCEGFVCT  LWCRKKLWRRRRRRRRRRR-COOH NV1G1707 NV1D3524 264 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWAPAPAPAPAPYGRKKRR QRRR-COOH NV1G1713 NV1D3525 265 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWAPAPAYGRKKRRQRRR- COOH NV1G1687 NV1D3526 266 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWYGRKKRRQRRR-COOH NV1G1699 NV1D3527 267 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWAPAPAPAPAP-COOH NV1G1675 NV1D3528 268 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWAPAPA-COOH NV1G1754 NV1D3529 269 GPRCQKWMQTCDAKRKCCEGFVCT LWCRKKLW-COOH NV1G1748 NV1D3530 270 GPSCQKWMQTCDAKRKCCEGFVCT LWCRKKLW-COOH NV1G1747 NV1D3531 271 GPYCQKWMQTCDAKRKCCEGFVCT LWCRKKLW-COOH NV1G1752 NV1D3532 272 GPACQKWMQTCDAKRKCCEGFVCT LWCRKKLW-COOH NV1G1722 NV1D3533 273 GPQCQKWMQTCDAKRKCCEGFSCT LWCRKKLW-COOH NV1G1744 NV1D3534 274 GPRCQKWMQTCDAKRKCCEGFSCT LWCRKKLW-COOH NV1G1742 NV1D3535 275 GPSCQKWMQTCDAKRKCCEGFSCTL WCRKKLW-COOH NV1G1723 NV1D3536 276 GPYCQKWMQTCDAKRKCCEGFSCTL WCRKKLW-COOH NV1G1745 NV1D3537 277 GPACQKWMQTCDAKRKCCEGFSCT LWCRKKLW-COOH NV1G1757 NV1D3538 278 GPRCQKWMQTCDRNRKCCEGFVCT LWCRKKLW-COOH NV1G1762 NV1D3539 279 GPSCQKWMQTCDRNRKCCEGFVCT LWCRKKLW-COOH NV1G1763 NV1D3540 280 GPYCQKWMQTCDRNRKCCEGFVCT LWCRKKLW-COOH NV1G1728 NV1D3541 281 GPACQKWMQTCDRNRKCCEGFVCT LWCRKKLW-COOH NV1G1730 NV1D3542 282 GPQCQKWMQTCDRNRKCCEGFSCT LWCRKKLW-COOH NV1G1760 NV1D3543 283 GPRCQKWMQTCDRNRKCCEGFSCT LWCRKKLW-COOH NV1G1727 NV1D3544 284 GPSCQKWMQTCDRNRKCCEGFSCT LWCRKKLW-COOH NV1G1729 NV1D3545 285 GPYCQKWMQTCDRNRKCCEGFSCT LWCRKKLW-COOH NV1G1867 NV1D3546 286 GPACQKWMQTCDRNRKCCEGFSCT LWCRKKLW-COOH NV1G1759 NV1D3547 287 GPRCQKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1758 NV1D3548 288 GPSCQKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1766 NV1D3549 289 GPYCQKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1761 NV1D3550 290 GPACQKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1726 NV1D3551 291 GPRCQKWMQTCDRERKCCEGFSCTL WCRKKLW-COOH NV1G1721 NV1D3552 292 GPSCQKWMQTCDRERKCCEGFSCTL WCRKKLW-COOH NV1G1765 NV1D3553 293 GPYCQKWMQTCDRERKCCEGFSCTL WCRKKLW-COOH NV1G1764 NV1D3554 294 GPACQKWMQTCDRERKCCEGFSCT LWCRKKLW-COOH NV1G1732 NV1D3555 295 GPRCQKWMQTCDAERKCCEGFSCT LWCKKKLW-COOH NV1G1862 NV1D3556 296 GPYCQKWMQTCDAERKCCEGFSCTL WCKKKLW-COOH NV1G1751 NV1D3558 297 GPRCQKWMQTCDANRKCCEGFSCT LWCKKKLW-COOH NV1G1866 NV1D3559 298 GPSCQKWMQTCDANRKCCEGFSCT LWCKKKLW-COOH NV1G1865 NV1D3560 299 GPYCQKWMQTCDANRKCCEGFSCT LWCKKKLW-COOH NV1G1716 NV1D3561 300 GPACQKWMQTCDANRKCCEGFSCT LWCKKKLW-COOH NV1G1724 NV1D3562 301 GPRCQKWMQTCDARRKCCEGFSCT LWCKKKLW-COOH NV1G1717 NV1D3563 302  GPSCQKWMQTCDARRKCCEGFSCTL WCKKKLW-COOH NV1G1743 NV1D3564 303 GPYCQKWMQTCDARRKCCEGFSCT LWCKKKLW-COOH NV1G1720 NV1D3565 304 GPACQKWMQTCDARRKCCEGFSCT LWCKKKLW-COOH NV1G1735 NV1D3566 305 GPRCQKWMQTCDAERKCCEGFVCT LWCKKKLW-COOH NV1G1734 NV1D3568 306 GPACQKWMQTCDAERKCCEGFVCT LWCKKKLW-COOH NV1G1741 NV1D3569 307 GPRCQKWMQTCDARRKCCEGFVCT LWCKKKLW-COOH NV1G1719 NV1D3570 308 GPSCQKWMQTCDARRKCCEGFVCT LWCKKKLW-COOH NV1G1718 NV1D3571 309 GPYCQKWMQTCDARRKCCEGFVCT LWCKKKLW-COOH NV1G1725 NV1D3572 310 GPACQKWMQTCDARRKCCEGFVCT LWCKKKLW-COOH NV1G1869 NV1D3573 311 GPRCQKWMQTCDANRKCCEGFVCT LWCKKKLW-COOH NV1G1755 NV1D3574 312 GPSCQKWMQTCDANRKCCEGFVCT LWCKKKLW-COOH NV1G1756 NV1D3575 313 GPYCQKWMQTCDANRKCCEGFVCT LWCKKKLW-COOH NV1G1746 NV1D3576 314 GPACQKWMQTCDANRKCCEGFVCT LWCKKKLW-COOH NV1G1733 NV1D3577 315 GPRCQKWMQTCDAERKCCEGFSCR LWCKKKLW-COOH NV1G1738 NV1D3578 316 GPYCQKWMQTCDAERKCCEGFSCR LWCKKKLW-COOH NV1G1737 NV1D3579 317 GPACQKWMQTCDAERKCCEGFSCR LWCKKKLW-COOH NV1G1740 NV1D3580 318 GPRCQKWMQTCDARRKCCEGFSCR LWCKKKLW-COOH NV1G1864 NV1D3581 319 GPSCQKWMQTCDARRKCCEGFSCR LWCKKKLW-COOH NV1G1739 NV1D3582 320 GPYCQKWMQTCDARRKCCEGFSCR LWCKKKLW-COOH NV1G1870 NV1D3583 321 GPACQKWMQTCDARRKCCEGFSCR LWCKKKLW-COOH NV1G1715 NV1D3584 322 GPRCQKWMQTCDANRKCCEGFSCR LWCKKKLW-COOH NV1G1753 NV1D3585 323 GPSCQKWMQTCDANRKCCEGFSCR LWCKKKLW-COOH NV1G1750 NV1D3586 324 GPYCQKWMQTCDANRKCCEGFSCR LWCKKKLW-COOH NV1G1750-NH2 NV1D3586-NH2 325 GPYCQKWMQTCDANRKCCEGFSCR LWCKKKLW-NH2 NV1G1749 NV1D3587 326 GPACQKWMQTCDANRKCCEGFSCR LWCKKKLW-COOH NV1G1871 NV1D3772 327 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWSHSNTQTLAKAPEHTG- COOH NV1G1839 NV1D3774 328 GPSHSNTQTLAKAPEHTGAPAPAPA PAPAPAPAPAPAPQCQKWMQTCDR ERKCCEGFVCTLWCRKKLW-COOH NV1G1877 NV1D3775 329 GPSHSNTQTLAKAPEHTGAPAPAPA PAPQCQKWMQTCDRERKCCEGFVC TLWCRKKLW-COOH NV1G1872 NV1D3777 330 GPSHSNTQTLAKAPEHTGQCQKWM QTCDRERKCCEGFVCTLWCRKKLW- COOH NV1G1941 NV1D3782 331 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKAW-COOH NV1G1990 NV1D3788 332 GPAAAAAQCQKWMQTCDRERKCC EGFVCTLWCRKKLW-COOH NV1G1991 NV1D3789 333 GPAPAPAQCQKWMQTCDRERKCCE GFVCTLWCRKKLW-COOH NV1G1989 NV1D3791 334 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWAAAAA-COOH NV1G1993 NV1D3792 335 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGGGGG-COOH NV1G1967 NV1D3793 336 GPCCNCSSKWCRDHSRCCGRGSAPA PAPAPAPAPAPAPAPAPGSQCQKW MQTCDRERKCCEGFVCTLWCRKKLW- COOH NV1G1969 NV1D3795 337 GPCCNCSSKWCRDHSRCCGSAPAPA PAPAPAPAPAPAPAPGSQCQKWMQ TCDRERKCCEGFVCTLWCRKKLW- COOH NV1G1974 NV1D3796 338 GPCCNCSSKWCRDHSRCCGSAPAPA PAPAPGSQCQKWMQTCDRERKCCE GFVCTLWCRKKLW-COOH NV1G1950 NV1D3797 339 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGSAPAPAPAPAPAPAPA PAPAPGSCCNCSSKWCRDHSRCC- COOH NV1G1948 NV1D3798 340 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGSAPAPAPAPAPAPAPA PAPAPGSCCNCSSKWCRDHSRCCGR- COOH NV1G2057 NV1D3799 341 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGSAPAPAPAPAPGSCCN CSSKWCRDHSRCC-COOH NV1G1954 NV1D3800 342 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGSAPAPAPAPAPGSCCN CSSKWCRDHSRCCGR-COOH NV1G1956 NV1D3801 343 GPSPGARAFAPAPAPAPAPQCQKW MQTCDRERKCCEGFVCTLWCRKKLW- COOH NV1G1961 NV1D3802 344 GPSPGARAFAPAPAQCQKWMQTC DRERKCCEGFVCTLWCRKKLW- COOH NV1G1960 NV1D3803 345 GPSPGARAFQCQKWMQTCDRERKC CEGFVCTLWCRKKLW-COOH NV1G1977 NV1D3804 346 GPDGPWRKMAPAPAPAPAPQCQK WMQTCDRERKCCEGFVCTLWCRKK LW-COOH NV1G1982 NV1D3805 347 GPDGPWRKMAPAPAQCQKWMQT CDRERKCCEGFVCTLWCRKKLW- COOH NV1G1984 NV1D3806 348 GPDGPWRKMQCQKWMQTCDRER KCCEGFVCTLWCRKKLW-COOH NV1G1985 NV1D3808 349 GPFGQKASSAPAPAQCQKWMQTC DRERKCCEGFVCTLWCRKKLW- COOH NV1G1983 NV1D3809 350 GPFGQKASSQCQKWMQTCDRERKC CEGFVCTLWCRKKLW-COOH NV1G1973 NV1D3810 351 GPQRFVTGHFGGLYPANGAPAPAPA PAPQCQKWMQTCDRERKCCEGFVC TLWCRKKLW-COOH NV1G1976 NV1D3811 352 GPQRFVTGHFGGLYPANGAPAPAQC QKWMQTCDRERKCCEGFVCTLWCR KKLW-COOH NV1G1980 NV1D3812 353 GPQRFVTGHFGGLYPANGQCQKW MQTCDRERKCCEGFVCTLWCRKKL W-COOH NV1G1952 NV1D3813 354 GPRRRRRRRRRRRAPAPAPAPAPQC QKWMQTCDRERKCCEGFVCTLWCR KKLW-COOH NV1G1957 NV1D3814 355 GPRRRRRRRRRRRAPAPAQCQKWM QTCDRERKCCEGFVCTLWCRKKLW- COOH NV1G1981 NV1D3815 356 GPRRRRRRRRRRRQCQKWMQTCDR ERKCCEGFVCTLWCRKKLW-COOH NV1G1959 NV1D3818 357 GPYGRKKRRQRRRQCQKWMQTCD RERKCCEGFVCTLWCRKKLW-COOH NV1G1986 NV1D3819 358 GPAPAPAPAPAPQCQKWMQTCDRE RKCCEGFVCTLWCRKKLW-COOH NV1G1968 NV1D3822 359 GPGWCGDPGATCGKLRLYCCSGFCD SYTKTCKDKSSAGGGGSAPAPAPAPA PAPAPAPAPAPAPAPAPAPAPGGGG SQCQKWMQTCDRERKCCEGFVCTL WCRKKLW-COOH NV1G1945 NV1D3823 360 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGGGGSAPAPAPAPAPA PAPAPAPAPAPAPAPAPAPGGGGSG WCGDPGATCGKLRLYCCSGFCDSYT KTCKDKSSA-COOH NV1G1972 NV1D3824 361 GPGWCGDPGATCGKLRLYCCSGFCD AYTKTCKDKSSAGGGGSAPAPAPAP APAPAPAPAPAPAPAPAPAPAPGGG GSQCQKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1946 NV1D3825 362 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGGGGSAPAPAPAPAPA PAPAPAPAPAPAPAPAPAPGGGGSG WCGDPGATCGKLRLYCCSGFCDAYT KTCKDKSSA-COOH NV1G1970 NV1D3826 363 GPGWCGDPGATCGKLRLYCCSGFCD CYTKTCKDKSSAGGGGSAPAPAPAP APAPAPAPAPAPAPAPAPAPAPGGG GSQCQKWMQTCDRERKCCEGFVCT LWCRKKLW-COOH NV1G1949 NV1D3828 364 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGSGGGGSAPAPAPAPA PAPAPAPAPAPGGGGSGSCCNCSSK WCRDHSRCCGR-COOH NV1G1951 NV1D3829 365 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWGSGGGGSAPAPAPAPA PAPAPAPAPAPGGGGSGSCCNCSSK WCRDHSRCC-COOH NV1G1971 NV1D3830 366 GPCCNCSSKWCRDHSRCCGRGSGG GGSAPAPAPAPAPAPAPAPAPAPGG GGSGSQCQKWMQTCDRERKCCEGF VCTLWCRKKLW-COOH NV1G1975 NV1D3832 367 GPCRTIGPSVCAPAPAPAPAPAPAPA PAPAPQCQKWMQTCDRERKCCEGF VCTLWCRKKLW-COOH NV1G1978 NV1D3833 368 GPCRTIGPSVCAPAPAPAPAPQCQK WMQTCDRERKCCEGFVCTLWCRKK LW-COOH NV1G1979 NV1D3834 369 GPCRTIGPSVCAPAPAQCQKWMQT CDRERKCCEGFVCTLWCRKKLW- COOH NV1G2043 NV1D3835 370 GPCRTIGPSVCQCQKWMQTCDRER KCCEGFVCTLWCRKKLW-COOH NV1G1955 NV1D3838 371 GPQCQKWMQTCDRERKCCEGFVCT LWCRKKLWAPAPACRTIGPSVC- COOH

In some embodiments disclosed herein, including in the numbered embodiments listed below, the isolated Protoxin-II variant inhibits human Nav1.7 activity with an IC₅₀ value of about 3×10⁻⁸ M or less.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the isolated Protoxin-II variant inhibits human Nav1.7 activity with an IC₅₀ value of between about 3×10⁻⁸ M to about 1×10⁻⁹ M.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the amino acid sequence GPQCX₁X₂WX₃QX₄CX₅X₆X₇X₈X₉CCX₁₀X₁₁X₁₂X₁₃CX₁₄LWCX₁₅KKLL (SEQ ID NO: 433), wherein

X₁ is Q, R, K, A or S;

X₂ is K, S, Q or R;

X₃ is M or F;

X₄ is T, S, R, K or Q;

X₅ is D or T;

X₆ is S, A or R;

X₇ is E, R, N, K, T or Q;

X₈ is R or K;

X₉ is K, Q, S or A;

X₁₀ is E, Q or D;

X₁₁ is G or Q;

X₁₂ is F or M;

X₁₃ is V or S;

X₁₄ is R or T; and

X₁₅ is K or R.

Exemplary Protoxin-II variants that inhibit human Nav1.7 activity with an IC₅₀ value of about 30×10⁻⁹ M or less are variants comprising the amino acid sequences of SEQ ID NOs: 56, 78, 111, 114, 117, 118, 119, 122, 123, 129, 130, 131, 132, 133, 134, 135, 136, 138, 139, 140, 141, 142, 145, 146, 147, 149, 150, 151, 152, 153, 154, 156, 158, 159, 165, 172, 173, 175, 177, 178, 183, 184, 185, 186, 189, 190, 193, 197, 199, 207, 210, 211, 216, 217, 224, 266, 273, 282, 335, 408, 409, 410, 422, 424, 425, 426, 427 and 428.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the isolated Protoxin-II variant selectively inhibits human Nav1.7. The Protoxin-II variants of the invention may be more selective towards Nav1.7 when compared to the recombinant Protoxin-II (SEQ ID NO: 2). In the QPatch electrophysiology assay, recombinant Protoxin-II has an IC₅₀ of about 2.2×10⁻⁹ M for Nav1.7 and an IC₅₀ of about 62×10⁻⁹ M for Nav1.6, and therefore the ratio of IC₅₀ for Nav1.6 to IC₅₀ for Nav1.7 about 28 fold. “Selectivity” or “selective” or “more selective” or “selectively blocks” or “selectively inhibits” when used herein refers to a Protoxin-II variant that has a ratio of IC₅₀ for Nav1.6 to IC₅₀ for Nav1.7 (IC₅₀(Nav1.6)/IC₅₀ (Nav1.7)) equal or over about 30. IC₅₀ for Nav1.6 may be assayed in a QPatch electrophysiology assay using cell lines stably expressing Nav1.6 using similar methods to those described for Nav1.7.

Residue positions in Protoxin-II that can be mutagenized to improve selectivity include residues 7, 11, 12, 14, 17, 18 and 19, and optionally residues 1, 20, 22 and 26 (residue numbering according to SEQ ID NO: 1). Exemplary substitutions to improve selectivity are Y1Q, W7Q, S11R, S11A, E12T, M19F, V20S, R22T, and K26R. Exemplary Protoxin-II variants with improved selectivity are variants of SEQ ID NOs: 56, 59, 65, 78, 111, 114, 117, 118, 119, 121, 122, 123, 129, 130, 133, 150, 190, 217, 281, 324, 325 or 326.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the sequence GPX₁CQKWMQX₂CDX₃X₄RKCCX₅GFX₆CX₇LWCX₈KKLW (SEQ ID NO: 405); wherein

X₁ is Y, Q, A, S or R;

X₅ is T or S;

X₃ is S, R or A;

X₄ is E, T or N;

X₅ is E or Q;

X₆ is V or S;

X₇ is R or T; and

X₈ is K or R;

wherein the Protoxin-II variant inhibits human Nav1.7 activity with an IC₅₀ value of about 3×10⁻⁸ M or less, and selectively inhibits human Nav1.7.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the isolated Protoxin-II variant comprises the sequence GPQCQKWMQX₁CDX₂X₃RKCCX₄GFX₅CX₆LWCX₈KKLW (SEQ ID NO: 406); wherein

X₁ is T or S;

X₅ is S, R or A;

X₃ is E, T or N;

X₄ is E or Q;

X₅ is V or S;

X₆ is R or T; and

X₇ is K or R.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the amino acid sequence that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 422 (GPYCQKWMQTCDSERKCCEGMVCRLWCKKKLL-COOH); wherein

-   -   the amino acid sequence has Q at position 7 and L at position         30, when residue numbering is according to SEQ ID NO: 1; and     -   the polypeptide inhibits human Nav1.7 activity. Protoxin-II         variants having substitutions W7Q and W30L have improved         folding, yield and selectivity when compared to the wild type         Protoxin-II.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated Protoxin-II variant comprising the amino acid sequence that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 78 (GPQCQKWMQTCDRERKCCEGFVCTLWCRKKLW-COOH); wherein

-   -   the amino acid sequence has Q at position 1, Q at position 7 and         F at position 19, when residue numbering is according to SEQ ID         NO: 1; the polypeptide inhibits human Nav1.7 activity with an         IC₅₀ value of about 30×10⁻⁹ M or less, wherein the IC₅₀ value is         measured using a veratridine-induced depolarization inhibition         assay using fluorescence resonance energy transfer (FRET) in the         presence of 25×10⁻⁶ M 3-veratroylveracevine in HEK293 cells         stably expressing human Nav1.7; and     -   the polypeptide selectively inhibits Nav1.7.

In some embodiments disclosed herein, including in the numbered embodiments listed below, the isolated Protoxin-II variant has a carboxylic acid, amide, methylamide or butylamide group at the C-terminus. C-terminal modifications may be generated via routine synthetic methods.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated fusion protein comprising the Protoxin-II variant of SEQ ID NOs: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 35, 357, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368 369, 370, 371, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 434, 435, 436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495, 496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 537, 538, 539, 540, 541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555, 556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645, 646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735 or 736. Such second polypeptides may be well known leader or secretory signal sequences, or synthetic sequences resulting for example from cloning steps, or tags such as hexahistidine tag (SEQ ID NO: 108). Such second polypeptide may be a half-life extending moiety. In one embodiment, the isolated fusion protein comprises the Protoxin-II variant of the invention conjugated to a half-life extending moiety.

Exemplary half-life extending moieties that may be used include well known human serum albumin, transthyretin (TTR), a thyroxine-binding globulin (TGB), albumin-binding domains, or an Fc or fragments thereof. Biologically suitable polymers or copolymers may also be used, for example ethylene glycol or polyethylene glycol (PEG) molecules, such as PEG5000 or PEG20000, dextran, polylysine, fatty acids and fatty acid esters of different chain lengths, for example laurate, myristate, stearate, arachidate, behenate, oleate, arachidonate, octanedioic acid, tetradecanedioic acid, octadecanedioic acid, docosanedioic acid, and the like, octane, or carbohydrates (dextran, cellulose, oligo- or polysaccharides). Exemplary moieties that can improve biodistribution include polyamination (putrescine, spermine, or spermidine etc.), halogenation (chlorine, bromine, fluorine, iodine), and glycosylation. These moieties may be direct fusions with the Protoxin-II variant polypeptides and may be generated by standard cloning and expression techniques. Alternatively, well known chemical coupling methods may be used to attach the moieties to recombinantly produced Protoxin-II variants of the invention. Alternatively, moieties can be incorporated as non-coded amino acids during solid phase peptide synthesis.

In another embodiment of the invention disclosed herein, including in the numbered embodiments listed below, the half-life extending moiety of the fusion protein of the invention is human serum albumin, variants of human serum albumin, albumin binding domain (ABD), or polyethylene glycol (PEG).

In another embodiment disclosed herein, including in the numbered embodiments listed below, the half-life extending moiety of is conjugated to the Protoxin-II variant via a linker. Suitable linkers are well known and include linkers having the sequence shown in SEQ ID NOs: 80 or 81.

Exemplary fusion proteins incorporating Protoxin-II variants of the invention are those having the polypeptide sequence of SEQ ID NOs: 83, 85, 87, 89, 91, 93, 95, 97, 99, 101 or 103.

Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below incorporating additional moieties may be compared for functionality by several well-known assays. For example, pharmacokinetic properties of Protoxin-II variants coupled to PEG may be evaluated in well known in vivo models.

Additional Protoxin-II variants and Protoxin-II variant fusion proteins are within the scope of the invention. Additional substitutions to the Protoxin-II variants of the invention can be made as long as the resulting variant or the fusion protein retains similar characteristics when compared to the parent peptide. Exemplary modifications are for example conservative substitutions that will result in Protoxin-II variants with similar characteristics to those of the parent molecules. Conservative replacements are those that take place within a family of amino acids that are related in their side chains. Genetically encoded amino acids can be divided into four families: (1) acidic (aspartate, glutamate); (2) basic (lysine, arginine, histidine); (3) nonpolar (alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan); and (4) uncharged polar (glycine, asparagine, glutamine, cysteine, serine, threonine, tyrosine). Phenylalanine, tryptophan, and tyrosine are sometimes classified jointly as aromatic amino acids. Alternatively, the amino acid repertoire can be grouped as (1) acidic (aspartate, glutamate); (2) basic (lysine, arginine histidine), (3) aliphatic (glycine, alanine, valine, leucine, isoleucine, serine, threonine), with serine and threonine optionally grouped separately as aliphatic-hydroxyl; (4) aromatic (phenylalanine, tyrosine, tryptophan); (5) amide (asparagine, glutamine); and (6) sulfur-containing (cysteine and methionine) (Stryer (ed.), Biochemistry, 2nd ed, WH Freeman and Co., 1981). Non-conservative substitutions can be made to the Protoxin-II variants that involve substitutions of amino acid residues between different classes of amino acids to improve properties of the Protoxin-II variants and Protoxin-II variant fusion proteins. Whether a change in the amino acid sequence of a polypeptide or fragment thereof results in a functional homolog can be readily determined by assessing the ability of the modified polypeptide or fragment to produce a response in a fashion similar to the unmodified polypeptide or fragment using the assays described herein. Peptides, polypeptides or proteins in which more than one replacement takes place can readily be tested in the same manner.

Another embodiment of the invention is an isolated family 3 spider venom cysteine knot peptide comprising at least one substitution at a position corresponding to position W7 and/or W30 of SEQ ID NO: 1. Family 3 spider toxins include 14 toxins with conserved C-terminal region, including, in addition to Protoxin-II, κ-TRTX-Gr2b, κ-TRTX-Gr2c, κ-TRTX-Ps1a, κ-TRTX-Ps1b, β-TRTX-Gr1b, κ-TRTX-Cj2a, κ-TRTX-Cj2b, κ-TRTX-Ec2c, β-TRTX-Gr1a, κ-TRTX-Ec2b, κ-TRTX-Ec2a and β/κ-TRTX-Cj2a and those shown in FIG. 14. Substitutions at positions W7 and/or W30 are expected to improve folding of the family 3 spider venom cysteine knot peptides.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is an isolated synthetic polynucleotide comprising a polynucleotide encoding the Protoxin-II variant of the invention.

Certain exemplary synthetic polynucleotides are disclosed herein, however, other synthetic polynucleotides which, given the degeneracy of the genetic code or codon preferences in a given expression system, encode the Protoxin-II variants and Protoxin-II variant fusion proteins of the invention are also within the scope of the invention. Exemplary synthetic polynucleotides are for example polynucleotide sequences shown in SEQ ID NOs: 84, 86, 88, 90, 92, 94, 96, 98, 100, 102 and 104, which encode the Protoxin-II variant fusion proteins of the invention. Those skilled in the art can readily identify the polynucleotide segments in the fusion proteins that encode the Protoxin-II variant itself. The synthetic polynucleotide sequences encoding the Protoxin-II variants or fusion proteins of the invention can be operably linked to one or more regulatory elements, such as a promoter and enhancer, that allow expression of the nucleotide sequence in the intended host cell. The synthetic polynucleotide may be a cDNA.

The polynucleotides of the invention may be produced by chemical synthesis such as solid phase polynucleotide synthesis on an automated polynucleotide synthesizer. Alternatively, the polynucleotides of the invention may be produced by other techniques such as PCR based duplication, vector based duplication, or restriction enzyme based DNA manipulation techniques. Techniques for producing or obtaining polynucleotides of known sequences are well known.

The polynucleotides of the invention may also comprise at least one non-coding sequence, such as transcribed but not translated sequences, termination signals, ribosome binding sites, mRNA stabilizing sequences, introns and polyadenylation signals. The polynucleotide sequences may also comprise additional sequences encoding additional amino acids. These additional polynucleotide sequences may, for example, encode a marker or well-known tag sequences such as a hexa-histidine (SEQ ID NO: 108) or a HA tag which facilitate the purification of fused polypeptides.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is a vector comprising the polynucleotide of the invention. Such vectors may be plasmid vectors, viral vectors, vectors for baculovirus expression, transposon based vectors or any other vector suitable for introduction of the polynucleotide of the invention into a given organism or genetic background by any means. For example, polynucleotides encoding the Protoxin-II variants or the Protoxin-II variant fusion proteins of the invention are inserted into an expression vector and may be operably linked to control sequences in the expression vector to ensure efficient expression, such as signal sequences, promoters (e.g. naturally associated or heterologous promoters), enhancer elements, and transcription termination sequences, and are chosen to be compatible with the host cell chosen to express the Protoxin-II variant or the Protoxin-II variant fusion protein of the invention. Once the vector has been incorporated into the appropriate host, the host is maintained under conditions suitable for high level expression of the proteins encoded by the incorporated polynucleotides.

Suitable expression vectors are typically replicable in the host organisms either as episomes or as an integral part of the host chromosomal DNA. Commonly, expression vectors contain selection markers such as ampicillin-resistance, hygromycin-resistance, tetracycline resistance, kanamycin resistance or neomycin resistance to permit detection of those cells transformed with the desired DNA sequences.

Suitable promoter and enhancer elements are known in the art. For expression in a bacterial cell, suitable promoters include, but are not limited to, lacl, lacZ, T3, T7, gpt, lambda P and trc. For expression in a eukaryotic cell, suitable promoters include, but are not limited to, light and/or heavy chain immunoglobulin gene promoter and enhancer elements; cytomegalovirus immediate early promoter; herpes simplex virus thymidine kinase promoter; early and late SV40 promoters; promoter present in long terminal repeats from a retrovirus; mouse metallothionein-I promoter; and various art-known tissue specific promoters. For expression in a yeast cell, a suitable promoter is a constitutive promoter such as an ADH1 PGK1, ENO or PYK1 promoter and the like, or a regulatable promoter such as a GAL1 or GAL10 promoter. Selection of the appropriate vector and promoter is well within the level of ordinary skill in the art.

Large numbers of suitable vectors and promoters are known to those of skill in the art; many are commercially available for generating recombinant constructs. The following vectors are provided by way of example. Bacterial: pBs, phagescript, PsiX174, pBluescript SK, pBs KS, pNH8a, pNH16a, pNH18a, pNH46a (Stratagene, La Jolla, Calif., USA); pTrc99A, pKK223-3, pKK233-3, pDR540, and pRIT5 (Pharmacia, Uppsala, Sweden). Eukaryotic: pWLneo, pSV2cat, pOG44, PXR1, pSG (Stratagene) pSVK3, pBPV, pMSG and pSVL (Pharmacia).

An exemplary vector for expression of the Protoxin-II variants or Protoxin-II variant fusion proteins is a vector having ampicillin-resistance selection marker, CMV promoter, CMV intron, signal peptide, neomycin resistance, f1 origin of replication, SV40 polyadenylation signal, and cDNA encoding the Protoxin-II variant or the Protoxin-II variant fusion protein of the invention.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is a host cell comprising the vector of the invention. The term “host cell” refers to a cell into which a vector has been introduced. It is understood that the term host cell is intended to refer not only to the particular subject cell but also to the progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not be identical to the parent cell, but are still included within the scope of the term “host cell” as used herein. Such host cells may be eukaryotic cells, prokaryotic cells, plant cells or archeal cells.

Escherichia coli, bacilli, such as Bacillus subtilis, and other enterobacteriaceae, such as Salmonella, Serratia, and various Pseudomonas species, are examples of prokaryotic host cells. Other microbes, such as yeast, are also useful for expression. Saccharomyces (e.g., S. cerevisiae) and Pichia are examples of suitable yeast host cells. Exemplary eukaryotic cells may be of mammalian, insect, avian or other animal origins. Mammalian eukaryotic cells include immortalized cell lines such as hybridomas or myeloma cell lines such as SP2/0 (American Type Culture Collection (ATCC), Manassas, Va., CRL-1581), NS0 (European Collection of Cell Cultures (ECACC), Salisbury, Wiltshire, UK, ECACC No. 85110503), FO (ATCC CRL-1646) and Ag653 (ATCC CRL-1580) murine cell lines. An exemplary human myeloma cell line is U266 (ATTC CRL-TIB-196). Other useful cell lines include those derived from Chinese Hamster Ovary (CHO) cells such as CHO-K1SV (Lonza Biologics, Walkersville, Md.), CHO-K1 (ATCC CRL-61) or DG44.

Introduction of a polynucleotide, such as a vector, into a host cell can be effected by methods well known to those skilled in the art. Exemplary methods are calcium phosphate transfection, DEAE-Dextran mediated transfection, microinjection, cationic lipid-mediated transfection and electroporation.

Another embodiment of the invention disclosed herein, including in the numbered embodiments listed below is a method for producing the Protoxin-II variant of the invention comprising the steps of providing a host cell of the invention; and culturing the host cell under conditions sufficient for the expression of at least one Protoxin-II variant of the invention.

Host cells can be cultured under any conditions suitable for maintaining or propagating a given type of host cell and sufficient for expressing a polypeptide. Culture conditions, media, and related methods sufficient for the expression of polypeptides are well known in the art. For example, many mammalian cell types can be aerobically cultured at 37° C. using appropriately buffered DMEM media while bacterial, yeast and other cell types may be cultured at 37° C. under appropriate atmospheric conditions in LB media.

In the methods of the invention disclosed herein, including in the numbered embodiments listed below, the expression of the Protoxin-II variant can be confirmed using a variety of well-known methods. For example, expression of a polypeptide can be confirmed using detection reagents, such as using SDS-PAGE or HPLC.

Another aspect of the invention is a method of modulating the activity of Nav1.7 in a biological tissue, the method comprising contacting the biological tissue expressing Nav1.7 with a Nav1.7-modulating amount of the Protoxin-II variant of the invention.

Methods of Treatment

Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be utilized in any therapy where it is desired to treat, reduce or alleviate symptoms of pain or other disorders of sensory or sympathetic neuron dysfunction.

Pain treated with the Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be any type of pain, such as chronic pain, acute pain, neuropathic pain, nociceptive pain, visceral pain, back pain, pain associated with inflammatory conditions, post-operative pain, thermal pain or pain associated with disease and degeneration.

Pain treated with the Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be Nav1.7-mediated pain.

Nav1.7-mediated pain as used herein refers to pain resulting at least partially from increased Nav1.7 channel activity.

The methods of the invention may be used to treat an animal patient belonging to any classification. Examples of such animals include mammals such as humans, rodents, dogs, cats and farm animals.

The pain and/or Nav1.7-mediated pain may result from one or more causes, such as peripheral neuropathy, central neuropathy, nerve compression or entrapment syndromes such as carpal tunnel syndrome, tarsus tunnel syndrome, ulnar nerve entrapment, compression radiculopathy, lumbar spinal stenosis, sciatic nerve compression, spinal root compression, intercostal neuralgia, compression radiculopathy and radicular lower back pain, spinal root lesions, neuritis, autoimmune diseases, general inflammation, chronic inflammatory conditions, arthritis, rheumatic diseases, lupus, osteoarthritis, general gastrointestinal disorders, colitis, gastric ulceration, duodenal ulcers, inflammatory bowel disorders, irritable bowel syndrome, pain associated with diarrhea, inflammatory eye disorders, inflammatory or unstable bladder disorders, psoriasis, skin complaints with inflammatory components, sunburn, carditis, dermatitis, myositis, neuritis, collagen vascular diseases, inflammatory pain and associated hyperalgesia and allodynia, neuropathic pain and associated hyperalgesia and allodynia, multiple sclerosis, demyelinating diseases, diabetes, diabetic neuropathy pain, causalgia, pain resulting from amputation or abscess, phantom limb pain, fracture pain, bone injury, direct trauma, HIV infection, acquired immune deficiency syndrome (“AIDS”), small pox infection, herpes infection, exposure to toxins or other foreign particles or molecules, invasive cancer, cancer, chemotherapy, radiotherapy, hormonal therapy, burns, congenital defect, dental pain, gout pain, fibromyalgias, encephalitis, chronic alcoholism, hypothyroidism, uremia and vitamin deficiencies, trigeminal neuralgia, stroke, thalamic pain syndrome, general headache, migraine, cluster headache, tension headache, mixed-vascular and non-vascular syndromes, sympathetically maintained pain, deafferentation syndromes, asthma, epithelial tissue damage or dysfunction, disturbances of visceral motility at respiratory, genitourinary, gastrointestinal or vascular regions, wounds, burns, allergic skin reactions, pruritis, vasomotor or allergic rhinitis, or bronchial disorders, dysmenorrhoea, pain during labor and delivery, dyspepsia, gastroesophageal reflux, pancreatitis, and visceralgia.

Other disorders of sensory or sympathetic neuron dysfunction that may be alleviated by the Protoxin-II variants of the invention include itch, cough and asthma. In mice, global deletion of the SCN9A gene leads to complete insensitivity to histamine-induced itch (Gingras et al., American Pain Society Meeting Abstract 2013 and U.S. Pat. Publ. No. 2012/0185956). This finding suggests that peptide Nav1.7 blockers may have utility in the treatment of itch, which may arise from various sources, such as dermatological or inflammatory disorders; or inflammatory disorders such as renal or hepatobiliary disorders, immunological disorders, medication reactions and unknown/idiopathic conditions, including dermatitis, psoriasis, eczema, insect sting or bite. Nav1.7 is also expressed in sensory nerves innervating the airways (Muroi et al., J Physiol. 2011 Dec. 1; 589(Pt 23):5663-76; Muroi et al., Am J Physiol Regul Integr Comp Physiol. 2013 Apr. 10), suggesting that peptide Nav1.7 blockers may be beneficial in the treatment of cough e.g., acute or chronic cough, or cough caused by irritation from gastroesophageal reflux disease, and inflammatory diseases of the airways such as asthma and allergy-related immune responses, bronchospasm, chronic obstructive pulmonary disease, chronic bronchitis, emphysema, and hiccups (hiccoughs, singultus). Silencing Nav1.7 in vivo in nodose ganglia of guinea pigs using shRNA nearly abolished the cough reflex induced by mechanical probing (Muroi et al., Am J Physiol Regul Integr Comp Physiol. 2013 Apr. 10).

One aspect of the invention is a method of alleviating or treating itch, cough or asthma in a subject by administering a therapeutically effective amount of the Protoxin-II variant of the invention disclosed herein, including in the numbered embodiments listed below to a subject in need thereof for a time sufficient to alleviate the itch, cough or asthma.

Another aspect of the invention is a method of alleviating or treating Nav1.7-mediated itch, Nav1.7-mediated cough or Nav1.7-mediated asthma in a subject by administering a therapeutically effective amount of the Protoxin-II variant of the invention disclosed herein, including in the numbered embodiments listed below to a subject in need thereof for a time sufficient to alleviate the itch, cough or asthma.

Nav1.7-mediated itch as used herein refers to itch resulting at least partially from increased Nav1.7 channel activity.

Nav1.7-mediated cough as used herein refers to cough resulting at least partially from increased Nav1.7 channel activity.

Nav1.7-mediated asthma as used herein refers to asthma resulting at least partially from increased Nav1.7 channel activity.

Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be tested for their effect in reducing or alleviating pain and/or Nav1.7-mediated pain using animal models described herein, and models such as the rat spinal nerve ligation (SNL) model of neuropathic pain, carageenan induced allodynia model, the Freund's complete adjuvant (CFA)-induced allodynia model, the thermal injury model, the formalin model and the Bennett Model, and other models as described in U.S. Pat. Appl. No. 2011/0124711 and U.S. Pat. No. 7,998,980. Carageenan induced allodynia and CFA-induced allodynia are models of inflammatory pain. The Bennett model provides an animal model for chronic pain including post-operative pain, complex regional pain syndrome, and reflex sympathetic dystrophy.

Any of the foregoing animal models may be used to evaluate the efficacy of Protoxin-II variants of the invention inhibitor in treating pain and/or NAv1.7-mediated pain. The efficacy of the Protoxin-II variants of the invention may be compared to a no treatment or placebo control. Additionally or alternatively, efficacy may be evaluated in comparison to one or more known pain-relieving medicaments.

The present invention provides methods of treating Nav1.7-mediated pain using the Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below. It has been discovered in the pending application by the inventors (U.S. Patent Application No. 61/781,276) that administration of Nav1.7 blocking peptides are efficacious in treating and/or alleviating pain in various animal models of pain, contrary to what was disclosed and suggested in the literature. While peptide inhibitors of Nav1.7 have been shown to be potent and/or selective towards Nav1.7 in in vitro cell culture models using overexpressed Nav1.7 or on isolated neurons in which the blood-nerve barrier is subverted through desheathing or hypertonic saline injection, they have so far proven non-efficacious in in vivo animal models of pain, where the lack of efficacy has been reported to result from the inability of the peptides to pass the blood-nerve barrier. Several publications describe lack of efficacy of Nav1.7 blocking peptides in animal models of pain or in isolated nerves. For example Hackel et al., Proc Natl Acad Sci 109:E2018-27, 2012, describes the inability of ProTx-II to inhibit action potential firing in isolated nerves unless the perineural barrier, which provides a diffusion barrier in this model, is compromised. ProTx-II was found non-efficacious in rodent models of acute and inflammatory pain; a likely explanation stated the inability of ProTx-II to cross the blood-nerve barrier (Schmalhofer et al., Mol Pharmacol 74:1476-1484, 2008). It has been proposed that Nav1.7 peptide toxin blockers have poor oral bioavailability and they are difficult to deliver to nerve endings, implying that their use as therapeutic agents remain limited (Dib-Hajj et al., Nature Rev Neuroscience 14, 49-62, 2013).

Nav1.7 is expressed in the peripheral nervous system e.g., in nociceptive dorsal root ganglions (DRG), most notably in nociceptive small-diameter DRG neurons, in particular in peripheral terminals in the skin, with little representation in the brain. Nav1.7 distribution (e.g. sensory ending) and physiology predispose it to a major role in transmitting painful stimuli.

One embodiment of the invention is a method of treating Nav1.7-mediated pain by administering a therapeutically effective amount of the Protoxin-II variant of the invention disclosed herein, including in the numbered embodiments listed below to a subject in need thereof for a time sufficient to treat the Nav1.7-mediated pain.

The Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be utilized in any therapy where it is desired to treat Nav1.7-mediated pain or other disorders of sensory or sympathetic neuron dysfunction. “Treat” or “treatment” of pain is meant to include partially or completely to prevent, stop, inhibit, reduce, or delay the perception of pain.

In some embodiments, the Nav1.7-mediated pain is chronic pain, acute pain, neuropathic pain, nociceptive pain, visceral pain, back pain, post-operative pain, thermal pain, phantom limb pain, or pain associated with inflammatory conditions, primary erythemalgia (PE), paraoxysmal extreme pain disorder (PEPD), osteoarthritis, rheumatoid arthritis, lumbar discectomy, pancreatitis, fibromyalgia, painful diabetic neuropathy (PDN), post-herpetic neuropathy (PHN), trigeminal neuralgia (TN), spinal cord injuries or multiple sclerosis, or pain associated with disease and degeneration.

Neuropathic pain includes for example painful diabetic neuropathy (PDN), post-herpetic neuropathy (PHN) or trigeminal neuralgia (TN). Other causes of neuropathic pain include spinal cord injuries, multiple sclerosis, phantom limb pain, post-stroke pain and HIV-associated pain. Conditions such as chronic back pain, osteoarthritis and cancer may also result in the generation of neuropathic-related pain and thus are potentially suitable for treatment with the Protoxin-II variants of the invention.

In another embodiment, the Nav1.7-mediated pain is associated with primary erythemalgia (PE), paraoxysmal extreme pain disorder (PEPD), osteoarthritis, rheumatoid arthritis, lumbar discectomy, pancreatitis or fibromyalgia.

In the methods of the invention, the Protoxin-II variants of the invention may be conjugated to a second polypeptide to form a fusion protein. Such fusion proteins are for example the well-known Fc fusions or fusions to human serum albumin to extend half-life of the peptide inhibitors. The conjugation may be a direct conjugation via a linker, such as a glycine-serine rich linker. Such linkers are well known in the art. The Protoxin-II variants of the invention incorporating additional moieties may be compared for their Nav1.7 blocking ability and efficacy in treatment or reducing pain using well known methods and those described herein.

Other disorders of sensory or sympathetic neuron dysfunction that can be treated with the Protoxin-II variants of the invention, including asthma, cough, heart-burn, itch, dermatitis, bladder instability, and Reynaud's disease.

Pharmaceutical Compositions

The Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be formulated in a pharmaceutically acceptable vehicle or carrier. One embodiment of the invention is a pharmaceutical composition comprising the isolated Protoxin-II variant of the invention and a pharmaceutically acceptable excipient.

A suitable vehicle or carrier may be water for injection, physiological saline solution or artificial cerebrospinal fluid, possibly supplemented with other materials common in compositions for parenteral administration. Neutral buffered saline or saline mixed with serum albumin are further exemplary vehicles. These solutions are sterile and generally free of particulate matter, and may be sterilized by conventional, well-known sterilization techniques (e.g., filtration). The compositions may contain pharmaceutically acceptable excipients as required to approximate physiological conditions, such as pH adjusting and buffering agents, stabilizing, thickening, lubricating and coloring agents, etc. Suitable vehicles and their formulation and packaging are described, for example, in Remington: The Science and Practice of Pharmacy (21st ed., Troy, D. ed., Lippincott Williams & Wilkins, Baltimore, Md. (2005) Chapters 40 and 41).

In the methods of the invention, the Protoxin-II variants of the invention may be administered by peripheral administration. “Peripheral administration” or “administered peripherally” means introducing an agent into a subject outside of the central nervous system. Peripheral administration encompasses any route of administration other than direct administration to the spine or brain.

Peripheral administration can be local or systemic. Local administration may be used to concentrate the therapeutic to the site of action, such as local administration to joints, surgical wounds, sites of injury/trauma, peripheral nerve fibers, various organs (GI, urogenital, etc) or inflamed tissues. Systemic administration results in delivery of a pharmaceutical composition to essentially the entire peripheral nervous system of the subject and may also result in delivery to the central nervous system depending on the properties of the composition.

Routes of peripheral administration encompass, without limitation, topical administration, intravenous, subcutaneous, intra-muscular, intra-articular or other injection, and implanted mini-pumps or other extended release devices or formulations.

Compounds may also be administered directly to the central nervous system e.g., intrathecal or intracisternal administration. Continuous intrathecal administration can be achieved via the use of implanted spinal drug pumps.

Pharmaceutical compositions of the invention include formulations involving the Protoxin-II variants of the invention in sustained- or controlled-delivery formulations. These formulations may be achieved through use of for example injectable microspheres, bio-erodible particles, microemulsions, nanoparticles, nanocapsules, macroemulsions, polymeric compounds (such as polyesters, polyamino acids, hydrogels, poly(lactic acid), polyglycolic acid or ethylene vinylacetate copolymers), beads or liposomes, hyaluronic acid or implantable drug delivery devices.

The Protoxin-II variants of the invention disclosed herein, including in the numbered embodiments listed below may be prepared for use for parenteral (subcutaneous, intramuscular or intravenous), intracerebral (intra-parenchymal), intrathecal, intra-articular, intracerebroventricular, intramuscular, intra-ocular, intra-arterial, intraportal, or intralesional routes; by sustained release systems or by implantation devices, or any other administration, particularly in the form of liquid solutions or suspensions; for buccal or sublingual administration such as in the form of tablets or capsules; or intranasally such as in form of powders, nasal drops or aerosols or certain agents; transdermally in a form of a gel, ointment, lotion, cream or dusting powder, suspension or patch delivery system with chemical enhancers to either modify the skin structure or to increase the drug concentration in the transdermal patch, or with agents that enable the application of formulations containing proteins and peptides onto the skin (Int. Pat. Publ. No. WO98/53847), or applications of electric fields to create transient transport pathways such as electroporation, or to increase the mobility of charged drugs through the skin such as iontophoresis, or application of ultrasound such as sonophoresis (U.S. Pat. Nos. 4,309,989 and 4,767,402). The composition also may be administered locally via implantation of a membrane, sponge or another appropriate material onto which the desired molecule has been absorbed or encapsulated.

In certain embodiments, where an implantation device is used, the device may be implanted into any suitable tissue or organ, and delivery of the desired molecule may be via diffusion, timed-release bolus, or continuous administration.

The concentration of the Protoxin-II variants of the invention or other peptide inhibitors of Nav1.7 in such pharmaceutical formulation can vary widely, for example from about 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or between 2% to 5%, up to as much as 15%, 20%, 30%, 40%, 50%, 60% or 70% by weight and will be selected primarily based on fluid volumes, viscosities and other factors, according to the particular mode of administration selected. The Protoxin-II variants of the invention can be lyophilized for storage and reconstituted in a suitable vehicle prior to use. This technique has been shown to be effective with conventional protein preparations. Lyophilization and reconstitution techniques are well known in the art.

An exemplary pharmaceutical compositions of the present invention may comprise Tris buffer of about pH 7.0-8.5, or acetate buffer of about pH 4.0-5.5, and may further include sorbitol, sucrose, Tween-20 and/or a suitable substitute thereof.

The appropriate therapeutically effective amount may be determined readily by those skilled in the art. A therapeutically effective amount refers to an amount or dosage sufficient to produce a desired result, i.e. to partially or completely prevent, stop, inhibit, reduce, or delay the perception of pain associated with any painful medical condition. The therapeutically effective amount may vary depending on the specific vehicle and the Protoxin-Ill variants of the invention selected, and is also dependent on a variety of factors and conditions related to the subject to be treated and the severity of the pain. For example, factors such as age, weight and health of the subject to be administered with the pharmaceutical compositions of the invention as well as dose response curves and toxicity data obtained in preclinical animal work could be among those considered. A determined dose may, if necessary, be repeated at appropriate time intervals selected as appropriate by a physician or other person skilled in the relevant art (e.g. nurse, veterinarian, or veterinary technician) during the treatment period. The determination of an effective amount or a therapeutically effective amount for a given agent is well within the ability of those skilled in the art.

Thus, a pharmaceutical composition of the invention for intramuscular injection could be prepared to contain 1 ml sterile buffered water, and between about 1 ng to about 100 mg, about 50 ng to about 30 mg or about 5 mg to about 25 mg of a Protoxin-II variant of the invention. Similarly, a pharmaceutical composition of the invention for intravenous infusion could be made up to contain about 250 ml of sterile Ringer's solution, and about 1 mg to about 30 mg or about 5 mg to about 25 mg of the Protoxin-II variants of the invention. Actual methods for preparing parenterally administrable compositions are well known and are described in more detail in, for example, “Remington's Pharmaceutical Science”, 15th ed., Mack Publishing Company, Easton, Pa.

Further Embodiments of the Invention

Set out below are certain further embodiments of the invention according to the disclosures elsewhere herein. Features from embodiments of the invention set out above described as relating to the invention disclosed herein also relate to each and every one of these further numbered embodiments.

-   -   1) An isolated Protoxin-II variant comprising the sequence         X₁X₂X₃CX₄X₅WX₆QX₇CX₈X₉X₁₀X₁₁X₁₂CCX₁₃X₁₄FX₁₅CX₁₆LWCX₁₇KKL W (SEQ         ID NO: 403), wherein         -   X₁ is G, P, A or deleted;         -   X₂ is P, A or deleted;         -   X₃ is S, Q, A, R or Y;         -   X₄ is Q, R, K, A or S;         -   X₅ is K, S, Q or R;         -   X₆ is M or F;         -   X₇ is T, S, R, K or Q;         -   X₈ is D or T;         -   X₉ is S, A or R;         -   X₁₀ is E, R, N, K, T or Q;         -   X₁₁ is R or K;         -   X₁₂ is K, Q, S or A;         -   X₁₃ is E, Q or D;         -   X₁₄ is G or Q;         -   X₁₅ is V or S;         -   X₁₆ is R or T; and         -   X₁₇ is K or R;         -   optionally having an N-terminal extension or a C-terminal             extension, wherein the polypeptide inhibits human Nav1.7             activity with an IC₅₀ value of about 1×10⁻⁷ M or less,             wherein the IC₅₀ value is measured using a             veratridine-induced depolarization inhibition assay using             fluorescence resonance energy transfer (FRET) in the             presence of 25×10⁻⁶ M 3-veratroylveracevine in HEK293 cells             stably expressing human Nav1.7.     -   2) The Protoxin-II variant of claim 1, wherein the N-terminal         extension comprises the amino acid sequence of SEQ ID NOs: 372,         373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384 or         385.     -   3) The Protoxin-II variant of claim 1 or 2, wherein the         C-terminal extension comprises the amino acid sequence of SEQ ID         NOs: 374, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396         or 397.     -   4) The Protoxin-II variant of claim 2 or 3, wherein the         N-terminal and/or the C-terminal extension is conjugated to the         Protoxin-II variant via a linker.     -   5) The Protoxin-II variant of claim 4, wherein the linker         comprises the amino acid sequence of SEQ ID NOs: 383, 392, 398,         399, 400, 401 or 402.     -   6) The isolated Protoxin-II variant of any of the claim 1-5,         comprising the amino acid sequence of SEQ ID NOs: 30, 40, 44,         52, 56, 56, 59, 65, 78, 109, 110, 111, 114, 117, 118, 119, 120,         121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133,         134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146,         147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,         162, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 177,         178, 179, 180, 182, 183, 184, 185, 186, 189, 190, 193, 195, 197,         199, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217,         218, 224, 226, 227, 231, 232, 243, 244, 245, 247, 249, 252, 255,         258, 261, 263, 264, 265, 266, 269, 270, 271, 272, 273, 274, 275,         276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288,         289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301,         302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314,         315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 332,         334, 335, 336, 337, 339, 340, 341, 342, 346, 351, 358, 359, 364,         366, 367, or 368.     -   7) The isolated Protoxin-II variant of any of the claims 1-6,         that inhibits human Nav1.7 activity with an IC₅₀ value of about         3×10⁻⁸ M or less.     -   8) The isolated Protoxin-II variant of claim 7 that inhibits         human Nav1.7 activity with an IC₅₀ value of between about 3×10⁻⁸         M to about 1×10⁻⁹ M.     -   9) The isolated Protoxin-II variant of claim 7 or 8 comprising         the amino acid sequence         GPQCX₁X₂WX₃QX₄CX₅X₆X₇X₈X₉CCX₁₀X₁₁FX₁₂CX₁₃LWCX₁₄KKLW (SEQ ID NO:         404), wherein         -   X₁ is Q, R, K, A or S;         -   X₂ is K, S, Q or R;         -   X₃ is M or F;         -   X₄ is T, S, R, K or Q;         -   X₅ is D or T;         -   X₆ is S, A or R;         -   X₇ is E, R, N, K, T or Q;         -   X₈ is R or K;         -   X₉ is K, Q, S or A;         -   X₁₀ is E, Q or D;         -   X₁₁ is G or Q;         -   X₁₂ is V or S;         -   X₁₃ is R or T; and         -   X₁₄ is K or R.     -   10) The isolated Protoxin-II variant of claim 9, comprising the         amino acid sequence of SEQ ID NOs: 56, 78, 111, 114, 117, 118,         119, 122, 123, 129, 130, 131, 132, 133, 134, 135, 136, 138, 139,         140, 141, 142, 145, 146, 147, 149, 150, 151, 152, 153, 154, 156,         158, 159, 165, 172, 173, 175, 177, 178, 183, 184, 185, 186, 189,         190, 193, 197, 199, 207, 210, 211, 216, 217, 224, 266, 273, 282         or 335.     -   11) The isolated Protoxin-II variant of any of the claims 1-10,         wherein the variant selectively inhibits human Nav1.7.     -   12) The isolated Protoxin-II variant of claim 11, comprising the         sequence GPX₁CQKWMQX₂CDX₃X₄RKCCX₅GFX₆CX₇LWCX₈KKLW (SEQ ID NO:         405); wherein         -   X₁ is Y, Q, A, S or R;         -   X₂ is T or S;         -   X₃ is S, R or A;         -   X₄ is E, T or N;         -   X₅ is E or Q;         -   X₆ is V or S;         -   X₇ is R or T; and         -   X₈ is K or R.     -   13) The isolated Protoxin-II variant of claim 12, comprising the         amino acid sequence of SEQ ID NOs: 56, 59, 65, 78, 111, 114,         117, 118, 119, 121, 122, 123, 129, 130, 133, 150, 190, 217, 281,         324, 325 or 326.     -   14) The isolated Protoxin-II variant of claim 12, comprising the         sequence GPQCQKWMQX₁CDX₂X₃RKCCX₄GFX₅CX₆LWCX₈KKLW (SEQ ID NO:         406); wherein         -   X₁ is T or S;         -   X₂ is S, R or A;         -   X₃ is E, T or N;         -   X₄ is E or Q;         -   X₅ is V or S;         -   X₆ is R or T; and         -   X₇ is K or R.     -   15) An isolated Protoxin-Ill variant comprising the amino acid         sequence that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or         99% identical to the amino acid sequence of SEQ ID NO: 78         (GPQCQKWMQTCDRERKCCEGFVCTLWCRKKLW-COOH), wherein         -   a) the amino acid sequence has Q at position 1, Q at             position 7 and F at position 19, when residue numbering is             according to SEQ ID NO: 1;         -   b) the polypeptide inhibits human Nav1.7 activity with an             IC₅₀ value of about 30×10⁻⁹ M or less, wherein the IC₅₀             value is measured using a veratridine-induced depolarization             inhibition assay using fluorescence resonance energy             transfer (FRET) in the presence of 25×10⁻⁶ M             3-veratroylveracevine in HEK293 cells stably expressing             human Nav1.7; and         -   c) the polypeptide selectively inhibits Nav1.7.     -   16) The isolated Protoxin-II variant of any of the claims 1-15,         having a free C-terminal carboxylic acid, amide, methylamide or         butylamide group.     -   17) An isolated fusion protein comprising the Protoxin-II         variant of any of the claims 1-16 conjugated to a half-life         extending moiety.     -   18) The fusion protein of claim 17, wherein the half-life         extending moiety is human serum albumin (HSA), albumin binding         domain (ABD), Fc or polyethylene glycol (PEG).     -   19) An isolated polynucleotide encoding the Protoxin-II variant         of claim 12 or 15.     -   20) A vector comprising the isolated polynucleotide of claim 19.     -   21) A host cell comprising the vector of claim 20.     -   22) A method of producing the isolated Protoxin-II variant,         comprising culturing the host cell of claim 21 and recovering         the Protoxin-II variant produced by the host cell.     -   23) A pharmaceutical composition comprising the isolated         Protoxin-II variant of claim 1, 6, 12, 13 or 15 and a         pharmaceutically acceptable excipient.     -   24) A method of treating Nav1.7-mediated pain in a subject,         comprising administering to a subject in need thereof an         effective amount of the Protoxin-II variant of any of the claims         1-16 to treat the pain.     -   25) The method of claim 24, wherein pain is chronic pain, acute         pain, neuropathic pain, cancer pain, nociceptive pain, visceral         pain, back pain, post-operative pain, thermal pain, phantom limb         pain, or pain associated with inflammatory conditions, primary         erythemalgia (PE), paraoxysmal extreme pain disorder (PEPD),         osteoarthritis, rheumatoid arthritis, lumbar discectomy,         pancreatitis, fibromyalgia, painful diabetic neuropathy (PDN),         post-herpetic neuropathy (PHN), trigeminal neuralgia (TN),         spinal cord injuries or multiple sclerosis.     -   26) The method of claim 24, wherein the Protoxin-II variant is         administered peripherally.     -   27) The method of claim 24, wherein the Protoxin-II variant is         administered locally to a joint, spinal cord, surgical wound,         sites of injury or trauma, peripheral nerve fibers, urogenital         organs, or inflamed tissues.     -   28) The method of claim 24, wherein the subject is a human.     -   29) The Protoxin-II variant of any of the claims 1-16 for use in         treating pain in a subject in need thereof.     -   30) The Protoxin-II variant for use according to claim 29,         wherein pain is chronic pain, acute pain, neuropathic pain,         cancer pain, nociceptive pain, visceral pain, back pain,         post-operative pain, thermal pain, phantom limb pain, or pain         associated with inflammatory conditions, primary erythemalgia         (PE), paraoxysmal extreme pain disorder (PEPD), osteoarthritis,         rheumatoid arthritis, lumbar discectomy, pancreatitis,         fibromyalgia, painful diabetic neuropathy (PDN), post-herpetic         neuropathy (PHN), trigeminal neuralgia (TN), spinal cord         injuries or multiple sclerosis.     -   31) The Protoxin-II variant for use according to claim 29 or 30,         wherein the Protoxin-II variant is administered peripherally.     -   32) The Protoxin-II variant for use according to claim 29, 30 or         31, wherein the Protoxin-II variant is administered locally to a         joint, spinal cord, surgical wound, sites of injury or trauma,         peripheral nerve fibers, urogenital organs, or inflamed tissues.

The present invention will now be described with reference to the following specific, non-limiting examples.

Example 1: Design and Generation of Protoxin-II Variants

A Protoxin-II single position limited amino acid substitution scanning library was designed to assess to what degree selectivity, peptide yield, and homogeneity can be improved.

Protoxin-II variants were designed as HRV3C protease cleavable HSA fusion proteins in the following format from N- to C-terminus: 6×His-HSA-linker-HRV3C cleavable peptide-Protoxin-II variant (“6×His” disclosed as SEQ ID NO: 108); linker being (GGGGSGGGGSGGGGSGGGGS; SEQ ID NO: 80, HSA having the sequence of SEQ ID NO: 106, HRV3C cleavable peptide having the sequence of SEQ ID NO: 82). Each Protoxin-II variant, after cleavage from HSA had a residual N-terminal GP from the cleavage site.

The variants were characterized in membrane depolarization assays using FLIPR® Tetra as described in Example 3 veratridine-induced depolarization inhibition assay, and in whole cell patch clamp experiments using the QPatch assay as described in Example 3.

Combinatorial libraries were designed to test for additive effects of select single position hits in an attempt to generate Nav1.7 antagonists with further improved potency and selectivity profile compared to the native peptide.

Construction of the Expression Vectors

The designed Protoxin-II variant genes were generated using synthetic gene assembly technology as described in U.S. Pat. No. 6,521,427. The amino acid sequences of the designed peptide variants were back-translated to DNA sequences using human high-frequency codons. The DNA sequence of each variant gene, together with a portion of vector DNA including the DNA cloning sites, was synthesized as multiple oligonucleotides, some of which contained degenerate codons, and assembled into full-length DNA fragments. The assembled DNA fragments were amplified by PCR and PCR products were subsequently cloned as a pool. Pooled PCR products were digested with the appropriate restriction enzymes and cloned into the designed expression vector in such a manner as to fuse each toxin variant gene to the signal peptide and the fusion partner (6×His-HSA-linker-HRV3C cleavable peptide (“6×His” disclosed as SEQ ID NO: 108) contained in the vector. Standard molecular biology techniques were used to identify a positive clone for each designed variant. The plasmid DNA from these positive clones was purified and sequence confirmed before expressing the Protoxin-II peptide variant fusion proteins using standard methods.

Protein Expression

HEK 293-F cells were maintained in 293 Freestyle™ media (Invitrogen Cat #12338) and split when the cell concentration was between 1.5 and 2.0×10⁶ cells per ml. The cells were grown in suspension, shaking at 125 RPM in a humidified incubator set at 37° C. and 8% CO₂. HEK 293F cells were transiently transfected using a DNA/lipid complex after they were diluted to 1.0×10⁶ cells per ml. To generate the complex, 1.25 μg DNA per ml of transfection was diluted in 1.0 ml of OptiPro media (Invitrogen Cat #12309) and 1.25 ml of Freestyle™ Max transfection reagent (Invitrogen Cat #16447) was diluted in 1.0 ml of OptiPro media. The DNA and Max transfection reagent were mixed together and incubated for 10 minutes at room temperature before adding to the cells. Transfected cells were placed in a humidified incubator set at 37° C. and 8% CO₂ for 4 days shaking at 125 RPM. The supernatant was separated from the cells by centrifugation at 5,000×g for 10 minutes and filtered through a 0.2 μm filter (Corning; Cat #431153), then concentrated 10 and 50 fold using an Amicon Ultra Concentrator 10K (Cat #UFC901096), and centrifuging for approximately 10 minutes at 3,750×g.

Example 2: Purification of Protoxin-II Variants

Protoxin-II variants were expressed as HSA fusion proteins as indicated in Example 1 and the Protoxin-II variant peptides were cleaved with HRV3C protease prior to purification. Two methodologies were tested for efficient purification of the Protoxin-II variants.

Protein Purification

Purification of Protoxin-II Variants by RP-HPLC

The secreted proteins were purified from the expression supernatants via IMAC using 1 ml HisTrap HP columns (GE Healthcare Cat#17-5247-01). The chromatography method was run using an AKTA Xpress and protein was eluted from the column using a step gradient of Imidazole. Peak fractions were pooled and digested overnight with HRV 3C protease (1 μg protease/150 μg fusion).

Cleaved peptide-fusion pools were further purified using a Dionex HPLC system with a reverse phase Phenomenex Luna 5 μm C18(2) column (Cat#00B-4252-PO-AX). Samples were eluted from the column with a 0-68% Acetonitrile (0.05% TFA) linear gradient. Elution fractions were pooled, lyophilized overnight and reconstituted in HEPES buffered saline, pH 7.4 (10 mM HEPES, 137 mM NaCl, 5.4 mM KCl, 5 mM glucose, 2 mM CaCl₂, 1 mM MgCl₂).

Table 4 shows yields of Protoxin-II variants purified by RP-HPLC. The average mg yield/L was 0.01615.

TABLE 4 Protoxin-II Protoxin-II Variant yield Variant yield Peptide ID (mg) Peptide ID (mg) NV1D816 0.0008 NV1D2496 0.0006 NV1D2511 0.0009 NV1D2503 0.0030 NV1D2513 0.0034 NV1D766 0.0054 NV1D2504 0.0071 NV1D770 0.0040 NV1D2260 0.0129 NV1D772 0.0015 NV1D2498 0.0079 NV1D792 0.0016 NV1D2499 0.0076 NV1D815 0.0008 NV1D2512 0.0061 NV1D768 0.0060 NV1D2267 0.0095 NV1D2508 0.0017 NV1D2507 0.0000 NV1D2501 0.0008 NV1D2509 0.0000 NV1D2296 0.0018 NV1D2305 0.0001 NV1D2292 0.0059 NV1D815 0.0021 NV1D750 0.0023 NV1D2506 0.0001 NV1D748 0.0036 NV1D2505 0.0006 NV1D774 0.0050 NV1D812 0.0001 NV1D786 0.0036 NV1D2510 0.0009 NV1D855 0.0008 NV1D769 0.0031 NV1D2312 0.0011 NV1D2497 0.0038 NV1D1410 0.0074 NV1D2500 0.0004 NV1D1415 0.0128 NV1D767 0.0004 NV1D751 0.0033 NV1D2502 0.0002 Purification of Protoxin-II Variants by Solid Phase Extraction (SPE)

The secreted proteins were purified from the expression supernatants via IMAC using 1 ml HisTrap HP columns (GE Healthcare Cat#17-5247-01). The chromatography method was run using an AKTA Xpress and protein was eluted from the column using a step gradient of Imidazole. Peak fractions were pooled and digested overnight with HRV3C protease (1 μg protease/150 μg fusion). The cleaved sample was loaded into a 50 kDa molecular weight cut off centrifugal filter unit (Millipore UFC805096) and cleaved peptide collected in the filtrate fraction.

Peptide pools were loaded onto a 96-well solid phase extraction block (Agilent Bond Elut Plexa A3969030) for further purification, desalting, and concentration. Blocks were used in conjunction with a vacuum manifold (Whatman). Peptide samples were loaded and washed in 0.05% TFA in water and eluted with a step gradient of acetonitrile with 0.05% TFA in water. Elution fractions were then lyophilized overnight and reconstituted in HEPES buffered saline, pH 7.4 (10 mM HEPES, 137 mM NaCl, 5.4 mM KCl, 5 mM glucose, 2 mM CaCl₂, 1 mM MgCl₂).

Peptides were reconstituted in supplemented HEPES buffered saline, pH 7.4 (10 mM HEPES, 137 mM NaCl, 5.4 mM KCl, 5 mM glucose, 2 mM CaCl₂, 1 mM MgCl₂) and absorbance was measured at 280 nm. Concentration values were then calculated using each sample's extinction coefficient. 2 μg of each peptide were loaded onto an Invitrogen NuPAGE® Novex® Bis-Tris Gel 15 well gel and run in MES buffer non-reduced.

Samples were analyzed on Agilent 1100 HPLC using 4-80% acetonitrile in 0.05% TFA linear gradient with a Phenomenex Luna C18(2) analytical column (Cat#00A-4041-B0). Concentrations of all peptides were normalized and 10 μl of each were injected for a total of 1.3 μg per sample. Absorbance at 220 nm was monitored and chromatograms analyzed were using Chromeleon software.

Table 5 shows yields (mg) of Protoxin-II variants purified by SPE. The average mg yield/L was 0.05353.

The benefits of the SPE purification process are ease and throughput of purification since samples are processed in parallel in a 96-well block rather than serially on RP-HPLC, and improvement in yield. There was, on average, more than 3-fold higher yield (mg/L) for variants purified by SPE versus RP-HPLC.

TABLE 5 Protoxin-II Protoxin-II Variant yield Variant yield Peptide ID (mg) Peptide ID (mg) NV1D12 0.0054 NV1D2734 0.0602 NV1D2659 0.0234 NV1D2772 0.2050 NV1D2664 0.0060 NV1D2775 0.2225 NV1D2666 0.0225 NV1D2738 0.0512 NV1D2708 0.0721 NV1D2740 0.0373 NV1D2725 0.0144 NV1D2733 0.1913 NV1D2739 0.0053 NV1D788 0.0000 NV1D2765 0.0097 NV1D757 0.0021 NV1D2748 0.0995 NV1D791 0.0007 NV1D2771 0.0103 NV1D2310 0.0011 NV1D2770 0.0121 NV1D2308 0.0014 NV1D2778 0.0644 NV1D778 0.0019 NV1D2782 0.0202 NV1D2294 0.0000 NV1D2756 0.0466 NV1D856 0.0047 NV1D2759 0.0218 NV1D2309 0.0023 NV1D2712 0.0558 NV1D846 0.0020 NV1D12 0.0127 NV1D2896 0.0504 NV1D2673 0.0625 NV1D2913 0.0203 NV1D2662 0.0433 NV1D2910 0.0253 NV1D2669 0.2661 NV1D2893 0.0569 NV1D2665 0.0389 NV1D2909 0.0195 NV1D2731 0.2547 NV1D2917 0.0339 NV1D2767 0.0238 NV1D2914 0.0201 NV1D2730 0.2566 NV1D2922 0.0554 NV1D2766 0.0198 NV1D2902 0.0061 NV1D2667 0.0050 NV1D2889 0.0022 NV1D2769 0.0142 NV1D2887 0.0025 NV1D2719 0.0675 NV1D2878 0.0272 NV1D2776 0.0633 NV1D2877 0.0129 NV1D2663 0.0344 NV1D2851 0.0029 NV1D2709 0.1841 NV1D2850 0.0026 NV1D2720 0.0538 NV1D2820 0.0020 NV1D12 0.0095 NV1D2819 0.0015 NV1D2773 0.1921 NV1D2814 0.0163 NV1D2810 0.0086 NV1D2918 0.0256 NV1D2732 0.0262 NV1D2921 0.0533 NV1D757 0.0026 NV1D2905 0.0126 NV1D791 0.0206 NV1D2906 0.0189 NV1D2310 0.0085 NV1D2881 0.0207 NV1D2308 0.0179 NV1D2882 0.0223 NV1D778 0.0094 NV1D2869 0.0038 NV1D856 0.0247 NV1D2870 0.0187 NV1D2309 0.0035 NV1D2867 0.0147 NV1D846 0.0043 NV1D2888 0.0045 NV1D2889 0.0107 NV1D2816 0.0133 NV1D2887 0.0061 NV1D2885 0.0025 NV1D2861 0.0469 NV1D2974 0.0418 NV1D2729 0.1101 NV1D2972 0.1089 NV1D2890 0.0088 NV1D2971 0.0407 NV1D2899 0.0402 NV1D2970 0.0557 NV1D2804 0.0044 NV1D2969 0.0799

Example 3: Characterization of Protoxin-II Variants

Select Protoxin-II variants were characterized in membrane depolarization and whole cell patch clamp assays to assess their potency and selectivity towards Nav1.7.

Veratridine-Induced Depolarization Inhibition Assay

The ability of the generated peptides to inhibit membrane depolarization induced by the Nav1.7 agonist veratridine (3-Veratroylveracevine; Biomol, Catalog# NA125) was measured with a veratridine-induced depolarization inhibition assay measuring decline in FRET (fluorescence resonance energy transfer) assay on a fluorescent resonance image plate reader (FLIRP Tetra®; Molecular Devices) DISBAC2(3) (Invitrogen, K1018) as an electron acceptor and PTS18 (Trisodium 8-octadecyloxypyrene-1,3,6-trisolfonate) (Sigma) as a donor by exciting the donor at 390-420 nm and measuring FRET at 515-575 nm.

HEK293 cells stably expressing human Nav1.7 were cultured in DMEM/F-12 media (1:1), supplemented with 10% fetal bovine serum, 1% penicillin/streptomycin, 400 μg/mL geneticin and 100 μM NEAAs (all reagents from Invitrogen). 50 μL of harvested cells were plated at 25,000 cells/well into poly-lysine coated 384-well black clear bottom plates. The plates were incubated at room temperature (RT) for 15 min followed by an overnight incubation at 37° C. All incubations were done in the dark unless otherwise stated. The next day, the wells were washed 4 times with assay buffer (137 mM NaCl, 4 mM KCl, 2 mM MgCl₂, 2 mM CaCl₂, 5 mM Glucose, 10 mM HEPES, pH 7.4), and resuspended in 25 μL of assay buffer. 2× stock (6 μM) of the PTS18 dye was prepared by suspending the dye in 10% pluronic F127 in DMSO at 1:1 (v/v ratio). 25 μL of the 2×PTS18 stock was added into the wells and the cells were stained for 30 min at RT, after which the dye was washed off with the assay buffer. Peptides were suspended at 3× their final concentration in the assay buffer containing 10 μM DISBAC2(3) and 400 μM VABSC-1 to suppress background fluorescence (Sigma, cat#201987). 25 μL/well of the suspended peptides were added into each well, and incubated for 60 minutes at RT. Depolarization was induced by 25 μM final concentration of veratridine (by adding 25 μL/well of 75 μM (3×) stock solution), and the reduction in the mean intensity of FRET dye fluorescence was measured 30-100 seconds after adding the agonist. A 1.3× dilution of each measured peptide occurred after adding veratridine by convention, the concentration at the beginning of the veratridine-induced depolarization inhibition assay is reported.

Concentration-response curves of synthetic Protoxin-II (Peptide International) were constructed in each experimental series and were used as controls. Fluorescence counts for each well were converted to % response by normalizing the signal to the difference between negative control (response to agonist veratridine alone) and positive control (response to veratridine in the presence of 10 μM tetracaine) values. For measurements, “spatial uniformity correction” (all fluorescence traces are normalized to the average initial starting intensity) and “subtract bias value” (subtract the initial starting intensity from each trace) were turned on in FLIPR® Tetra. Each data point represented the response in an individual well. All individual data points were used in a non-linear least-squares fitting procedure to find the best fit to a Hill function using Origin (Microcal). IC₅₀ values were extracted from the resultant fitted curve. The mean responses of the positive (P) and negative (N) controls were used to calculate the % response in a well as follows: % response=100*(N−R)/(N−P).

Assay plates were accepted if the potency of control antagonists for that day were within ±0.5 log units of their historical mean.

QPatch Assay

HEK293 cells stably expressing human Nav1.5 (SEQ ID NO: 105), Nav1.7 (SEQ ID NO: 79) or Nav1.6 (SEQ ID NO: 407) were cultured in DMEM/F-12 media (1:1), supplemented with 10% fetal bovine serum, 1% penicillin/streptomycin, 400 μg/mL Geneticin and 100 μM NEAAs (all reagents from Invitrogen). Cells were maintained at 37° C. and in 5% CO₂ and assayed upon reaching ˜50-90% confluency. CHO cells stably expressing human Nav1.6 in a tetracycline-inducible manner (SEQ ID NO: 407) were cultured in HAMs F12, supplemented with 10% fetal bovine serum, 1% penicillin/streptomycin, 10 μg/mL Blasticidin and 400 μg/mL Zeocin. Cells were maintained at 37° C. and in 5% CO2, and assayed upon reaching ˜50-90% confluency. Nav1.6 expression was induced with 1 μg/ml of tetracycline, 24-48 h prior to an experiment.

Before testing in QPatch HT (Sophion), cells were first dissociated using 0.05% trypsin (5 min at 37° C.), resuspended in CHO-S-SFM media (Life Technologies) and gently triturated to break up cell clumps. Cell density was adjusted to 1-2×10⁶/mL with the same media and cells were the transferred to a cell “hotel” in QPatch HT and used in experiments for several hours. For giga-ohm seal formation and whole-cell patch clamp recording, the extracellular solution contained 137 mM NaCl, 5.4 mM KCl, 1 mM MgCl₂, 2 mM CaCl₂, 5 mM glucose, and 10 mM HEPES, pH=7.4 and osmolarity=315 mOsm. The intracellular solution contained 135 mM CsF, 10 mM CsCl, 5 mM EGTA, 5 mM NaCl and 10 mM HEPES, pH=7.3 and osmolarity=290 mOsm. The voltage protocol used in the assay was as follows. From a holding potential of −75 mV (Nav1.7), −60 mV (Nav1.6), or −105 mV (Nav1.5) cells were first hyperpolarized to −120 mV for 2 sec and then depolarized to 0 mV for 5 ms before returning to the holding potential. This protocol was repeated once every 60 sec during liquid applications (see below). Cells were otherwise held at the holding potential when the above voltage protocol was not executed. Upon establishment of the whole-cell recording configuration, a total of five applications of the extracellular solution (all containing 0.1% bovine serum albumin (BSA) with or without test compound, except for the last application, which contained 1 μM TTX or 10 mM lidocaine as a positive control) were made on to cells being recorded. The first liquid application contained only the control buffer (5 μl). The voltage protocol was executed 10 times (for a total duration of 10 min) five sec after the application. The next three liquid applications (5 μl each) contained a test compound (same compound at the same concentration for all three applications) or control buffer (for control cells only). Five seconds after each of these applications, the voltage protocol was again executed 10 times (also once per min). The last application contained positive (composed of three 10 μl sub-applications, each separated by 2 sec), five seconds after which the same voltage protocol was executed twice to obtain the baseline current. Currents were sampled at 25 kHz and filtered at 5 kHz with an 8-pole Bessle filter. The series resistance compensation level was set at 80%. For each cell, the peak current amplitude at 0 mV for each current trace in the first four liquid applications was first subtracted from that of the last trace in the presence of positive control and then normalized to that of the last trace in the first (control buffer) application as % inhibition. To control for current rundown, this (% inhibition) value for each cell in the presence of a test compound was further normalized to the average % inhibition value for control (typically 5-6) cells in the same experiment. The mean of the last two such values in the last compound application (i.e., the corrected % inhibition value for each concentration of a test compound) were taken as the % inhibition value for each cell at the particular compound concentration tested. The % inhibition values for all cells tested at each compound concentration were averaged and used in concentration response calculations. All experiments were performed at room temperature (˜22° C.). Data are expressed as mean±se. Wild type Protoxin-II was included in each experiment as a positive control. Data were accepted only if the potency of Protoxin-II was within ±0.5 log units of its historical mean.

IC₅₀ values for Nav1.7 for select Protoxin-II variants obtained using the veratridine-induced depolarization inhibition assay are shown in Table 6.

TABLE 6 hNav1.7 VERATRIDINE- INDUCED Protoxin-II Protoxin-II DEPOLAR- Variant variant Peptide IZATION Protein ID Peptide ID SEQ ID NO: IC₅₀ (nM) NV1D12_5 NV1D12 2 4.1 ± 3.6 NV1G1045 NV1D791 11 4.8 ± 0.4 NV1D1332_1 NV1D1332 12 6.7 ± 0.5 NV1D1336_1 NV1D1336 14 10.5 ± 1.2  NV1D1337_1 NV1D1337 15 10.3 ± 1.0  NV1G1049 NV1D2308 16 4.5 ± 0.4 NV1G953 NV1D2670 17 22.2 ± 3.3  NV1G951 NV1D2674 18 4.0 ± 0.2 NV1G963 NV1D2671 20 31.5 ± 6.4  NV1G949 NV1D2675 21 4.3 ± 0.3 NV1G977 NV1D2665 22 4.9 ± 0.4 NV1G957 NV1D2668 23 17.5 ± 2.6  NV1G965 NV1D2672 24 4.5 ± 0.3 NV1G973 NV1D2662 25 4.0 ± 0.4 NV1G975 NV1D2669 26 18.4 ± 5.7  NV1G971 NV1D2673 27 4.3 ± 0.5 NV1G995 NV1D2663 28 4.2 ± 0.4 NV1G961 NV1D2676 29 26.5 ± 2.9  NV1G911 NV1D2666 30 66.5 ± 36.7 NV1G1133 NV1D2816 31  667 ± 93.6 NV1G905 NV1D2735 32 60.0 ± 16.2 NV1G979 NV1D2731 34 20.7 ± 7.2  NV1G1097 NV1D2810 35  339 ± 5750 NV1G1099 NV1D2732 36  126 ± 26.9 NV1G1011 NV1D2740 37 3.6 ± 9.9 NV1G1105 NV1D2729 39 8.0 ± 0.9 NV1G1013 NV1D2733 40 7.5 ± 2.9 NV1G1095 NV1D2814 41  754 ± 51.3 NV1G983 NV1D2730 43 25.5 ± 4.3  NV1G1003 NV1D2734 44 13.4 ± 0.8  NV1G1009 NV1D2738 45 2.6 ± 0.2 NV1G1129 NV1D2867 49 >1000 NV1G1121 NV1D2881 50  488 ± 72.2 NV1G1123 NV1D2882 51  857 ± 65.7 NV1G899 NV1D2774 52 50.5 ± 15.2 NV1G1103 NV1D2861 54 >1000 NV1G1127 NV1D2870 55  784 ± 84.8 NV1G1007 NV1D2775 56 25.4 ± 2.0  NV1G1067 NV1D2893 57 75.5 ± 10.5 NV1G1005 NV1D2772 59 15.6 ± 1.8  NV1G1061 NV1D2896 60 80.3 ± 7.1  NV1G1085 NV1D2877 61  441 ± 73.3 NV1G1083 NV1D2878 62  680 ± 40.7 NV1G1079 NV1D2889 64 12.1 ± 1.5  NV1G1001 NV1D2773 65 18.8 ± 1.5  NV1G1107 NV1D2890 66 25.8 ± 4.2  NV1G1109 NV1D2899 67 33.3 ± 6.7  NV1G1117 NV1D2905 68  713 ± 87.3 NV1G1119 NV1D2906 69  940 ± 86.7 NV1G1115 NV1D2921 70  586 ± 71.7 NV1G1075 NV1D2922 71  204 ± 45.7 NV1G1069 NV1D2909 72 97.1 ± 10.1 NV1G1065 NV1D2910 73  441 ± 41.7 NV1G1063 NV1D2913 74 79.7 ± 9.3  NV1G1073 NV1D2914 75 135 ± 7.8  NV1G1071 NV1D2917 76  197 ± 48.3 NV1G1113 NV1D2918 77  983 ± 98.7 NV1G1153 NV1D3034 78 10.3 ± 2.1 

Select Protoxin-II variants were tested for selectivity against human Nav1.5 using QPatch. IC₅₀ values for both Nav1.7 and Nav1.5 for select peptides obtained using QPatch are shown in Table 7.

TABLE 7 Protoxin-II Protoxin-II hNav1.7 hNav1.5 Variant variant Peptide QPatch Protein ID Peptide ID SEQ ID NO: IC₅₀ (nM) IC₅₀ (nM) NV1D12_5 NV1D12 2 2.2 ± 1.3 >1000 NV1G899 NV1D2774 52 18.7 ± 13.6 >3000 NV1G1007 NV1D2775 56 4.0 ± 8.9 >3000 NV1G1005 NV1D2772 59 6.2 ± 3.2 >3000 NV1G1001 NV1D2773 65 4.3 ± 3.3 >3000 NV1G1153 NV1D3034 78 4.3 ± 4.3 >1000

Example 4. Generation and Characterization of Combinatorial Protoxin-II Variants

Combinatorial libraries were designed to test for additive effects of select single position hits in an attempt to generate Nav1.7 antagonists with further improved potency and selectivity profile compared to the native peptide using several approaches.

A limited amino acid scan was conducted at all non-cysteine Protoxin-II positions using A, D, Q, R, K and S for diversification. In these experiments, Protoxin-II was expressed and tested as monovalent Fc fusion protein as described in Example 1. From this scan, substitutions Y1Q, W7Q, S11A, were identified that improved potency and/or selectivity of the resulting variants.

A full amino acid scan (excluding cys and trp) at positions M6 and M19 was also conducted. M19F substitution was identified from this scan that improved potency and/or selectivity of the resulting variants.

Protoxin-II/Huwentoxin-IV single position chimeras were designed bidirectionally. The purpose of this library was to obtain Protoxin-II variants that retained potency and selectivity profile of the wild type Protoxin-II and would achieve beneficial refolding properties associated with Huwentoxin-IV. Substitutions R22T and E12N were identified from this scan.

Peptide NV1G1153 was further engineered by diversifying position Y1 by a limited amino acid scan using R, K, T, A, D, E, Q and S, and by charge cluster engineering, where all sets of charged residues in the three-dimensional structure of the peptide (D10/E12, K4/E17, D10/E12/R13) were mutated.

N- and C-terminal extensions were introduced to select peptides, including NV1G1153 with the purpose of improving peptide distribution to the site of action and of improving half-life of the peptides without significantly increasing the molecular weight of the resulting peptide. The N- and C-terminal extensions that were used are shown in Table 8 and 9, respectively, and are described in Oi et. al., Neuroscience Letters 434, 266-272, 2008; Whitney et. al., Nature Biotechnology 2011 29:4, 352-356; Sockolosky et. al., (2012) 109:40, 16095-16100. Cell penetrating peptides HIV Tat and polyarginine were also used. Various linkers were used to couple the Protoxin-II variant to the N- and/or C-terminal extensions. The linkers used are shown in Table 10.

Protoxin-II variants from each campaign were tested for their potency and selectivity for Nav1.7 using methods described in Example 3. The amino acid sequences of the variants that inhibited Nav1.7 with an IC₅₀ value of 200 nM or less are shown in Table 3. Table 11 shows the amino acid substitutions in select variant when compared to the wild type Protoxin-Ill, and the IC₅₀ values for Nav1.7 inhibition in the veratridine-induced depolarization inhibition assay.

TABLE 8 N-terminal extension Amino acid sequence SEQ ID NO: GPAAAAA 372 GPAPAPA 373 GGGGG 374 GPCCNCSSKWCRDHSRCC 375 GPSPGARAF 376 GPDGPWRKM 377 GPFGQKASS 378 GPCRTIGPSVC 379 GPSHSNTQTLAKAPEHTG 380 GPQRFVTGHFGGLYPANG 381 GPGWCGDPGATCGKLRLYCCSGFCDSYTKTCKDKSSA 382 APAPAPAPAP 383 GPYGRKKRRQRRR 384 GPRRRRRRRRRRR 385

TABLE 9 C-terminal extensions SEQ ID Amino acid sequence NO: CRTIGPSVC 386 YGRKKRRQRRR 387 GGGGG 374 DGPWRKM 388 CCNCSSKWCRDHSRCC 389 RRRRRRRRRRR 390 SHSNTQTLAKAPEHTG 391 APAPA 392 AAAAA 393 FGQKASS 394 QRFVTGHFGGLYPANG 395 SPGARAF 396 GPGWCGDPGATCGKLRLYCCSGFCDAYTKTCKDKSSA 397

TABLE 10 Linkers Amino acid sequence SEQ ID NO: GSAPAPAPAPAPGS 398 GSAPAPAPAPAPAPAPAPAPAPGS 399 GGGGSAPAPAPAPAPAPAPAPAPAPAPAPAPA 400 PAPGGGGS APAPA 392 GSGGGGSAPAPAPAPAPAPAPAPAPAPGGGGS 401 GS APAPAPAPAP 383 APAPAPAPAPAPAPAPAPAP 402

TABLE 11 Protoxin-II Protein Nav1.7 variant SEQ ID IC₅₀ Protein name peptide name NO: Substitutions (nM) SE NV1G1728 NV1D3541 281 Y1A, W7Q, S11R, E12N, M19F, 9.4 1.2 R22T, K26R NV1G1870 NV1D3583 321 Y1A, W7Q, S11A, E12R, M19F, 13.1 1.57 V20S NV1G1752 NV1D3532 272 Y1A, W7Q, S11A, E12K, M19F, 17.3 2 R22T, K26R NV1G1749 NV1D3587 326 Y1A, W7Q, S11A, E12N, M19F, 18.3 2.6 V20S NV1G1725 NV1D3572 310 Y1A, W7Q, S11A, E12R, M19F, 19.8 2.2 R22T NV1G1745 NV1D3537 277 Y1A, W7Q, S11A, E12K, M19F, 21.4 4.1 V20S, R22T, K26R NV1G1720 NV1D3565 304 Y1A, W7Q, S11A, E12R, M19F, 23 2.8 V20S, R22T NV1G1761 NV1D3550 290 Y1A, W7Q, S11R, M19F, R22T, 25.8 2.7 K26R NV1G1746 NV1D3576 314 Y1A, W7Q, S11A, E12N, M19F, 26.7 5.2 R22T NV1G979 NV1D2731 34 Y1A, W7Q, S11A 20.7 7.2 NV1G953 NV1D2670 17 Y1A, W7Q 22.2 3.3 NV1G1519 NV1D3006 133 Y1Q, W7Q, S11A, E12R, M19F 4.03 1.05 NV1G1007- NV1D2775- 111 Y1Q, W7Q, S11A, M19F 5.06 0.473 NH2 NH2 NV1G1517 NV1D3004 131 Y1Q, W7Q, S11R, M19F 6.23 1.56 (-GP) N-Ac- (-GP) N-Ac- 114 Y1Q, W7Q, S11A, M19F, V20S, 6.43 1.06 NV1G1137- NV1D2974- R22T NH2 NH2 NV1G1776 NV1D3339 172 Y1Q, Q3R, W7Q, S11R, M19F, 6.57 0.675 R22T, K26R NV1G1153- NV1D3034- 119 Y1Q, W7Q, S11R, M19F, R22T, 7.1 0.9 NH-methyl NH-methyl K26R (-GP) N-Ac- (-GP) N-Ac- 121 Y1Q, W7Q, S11R, M19F, R22T, 7.63 1.04 NV1G1153- NV1D3034- K26R NH2 NH2 NV1G1523 NV1D3012 135 Y1Q, W7Q, S11R, E12N, M19F 7.74 0.904 NV1G1515 NV1D3005 132 Y1Q, W7Q, S11A, E12N, M19F 7.83 1.38 NV1G1187 NV1D3015 138 Y1Q, W7Q, S11R, M19F, K26R 8.86 2.28 NV1G1521 NV1D3018 141 Y1Q, W7Q, S11A, E12N, M19F, 9.79 2.91 K26R NV1G1267 NV1D3044 150 Y1Q, W7Q, S11R, E12N, M19F, 9.8 0.849 R22T, K26R NV1G1153 NV1D3034 78 Y1Q, W7Q, S11R, M19F, R22T, 10.3 2.14 K26R NV1G1836 NV1D3359 190 Y1Q, W7Q, T8S, S11R, M19F, 10.5 0.739 R22T, K26R NV1G1593 NV1D3050 153 Y1Q, W7Q, S11R, E12K, M19F 10.8 1.3 NV1G1215 NV1D3048 152 Y1Q, W7Q, S11A, E12K, M19F 11.1 1.05 NV1G1868 NV1D3353 185 Y1Q, W7Q, T8R, S11R, M19F, 11.2 1.25 R22T, K26R NV1G1525 NV1D3013 136 Y1Q, W7Q, S11R, E12R, M19F 11.3 1.83 NV1G1775 NV1D3340 173 Y1Q, Q3K, W7Q, S11R, M19F, 11.5 0.798 R22T, K26R NV1G1833 NV1D3381 210 Y1Q, W7Q, S11RK14Q, M19F, 12.2 1.56 R22T, K26R NV1G1153- NV1D3034- 117 Y1Q, W7Q, S11R, M19F, R22T, 12.2 1 NH2 NH2 K26R NV1G1777 NV1D3342 175 Y1Q, Q3A, W7Q, S11R, M19F, 12.8 2.67 R22T, K26R NV1G1259 NV1D3058 158 Y1Q, W7Q, S11A, E12K, M19F, 12.9 1.29 R22T, K26R NV1G1511 NV1D3032 146 Y1Q, W7Q, S11R, E12N, M19F, 13 203 K26R NV1G1527 NV1D3031 145 Y1Q, W7Q, S11R, E12R, M19F, 13 1.36 R22T NV1G1265 NV1D3062 159 Y1Q, W7Q, S11R, E12K, M19F, 13.2 1.43 R22T, K26R NV1G1781 NV1D3388 217 Y1Q, W7Q, S11RE17Q, M19F, 13.5 1.14 R22T, K26R NV1G1824 NV1D3354 186 Y1Q, W7Q, T8K, S11R, M19F, 13.9 1.12 R22T, K26R NV1G1772 NV1D3352 184 Y1Q, K4S, W7Q, S11R, M19F, 14.2 2.01 R22T, K26R NV1G1509 NV1D3033 147 Y1Q, W7Q, S11R, E12R, M19F, 14.5 2.18 K26R NV1G1779 NV1D3351 183 Y1Q, K4Q, W7Q, S11R, M19F, 15.3 2.39 R22T, K26R NV1G1687 NV1D3526 266 Y1Q, W7Q, S11R, M19F, R22T, 15.4 K26R NV1G1269 NV1D3045 151 Y1Q, W7Q, S11R, E12R, M19F, 15.6 1.39 R22T, K26R NV1G1623 NV1D3056 156 Y1Q, W7Q, S11R, E12K, M19F, 16.2 2.99 R22T NV1G1859 NV1D3376 205 Y1Q, W7Q, S11R, K14R, M19F, 16.3 2.53 R22T, K26R NV1G1153- NV1D3034- 118 Y1Q, W7Q, S11R, M19F, R22T, 16.6 1.4 NH-butyl NH-butyl K26R NV1G1211 NV1D3036 149 Y1Q, W7Q, S11A, E12R, M19F, 17.2 1.55 R22T, K26R NV1G1885 NV1D3254 165 Y1Q, W7Q, S11A, M19F 17.5 2.45 NV1G1730 NV1D3542 282 Y1Q, W7Q, S11R, E12N, M19F, 17.7 2.5 V20S, R22T, K26R NV1G1263 NV1D3051 154 Y1Q, W7Q, S11A, E12K, M19F, 17.9 1.78 R22T NV1G1818 NV1D3368 122 Y1Q, W7Q, S11R, E12T, M19F, 17.9 1.89 R22T, K26R NV1G1153 NV1D3034 116 Y1Q, W7Q, S11R, M19F, R22T, 18 2.5 (synthetic) K26R NV1G1823 NV1D3367 197 Y1Q, W7Q, S11R, E12Q, M19F, 18.6 2.17 R22T, K26R NV1G1820 NV1D3362 193 Y1Q, W7Q, D10T, S11R, M19F, 20.1 2.32 R22T, K26R NV1G1811 NV1D3369 199 Y1Q, W7Q, S11R, R13K, M19F, 20.4 2.44 R22T, K26R NV1G1810 NV1D3358 189 Y1Q, W7Q, T8Q, S11R, M19F, 20.5 2.11 R22T, K26R NV1G1818- NV1D3368- 123 Y1Q, W7Q, S11R, E12T, M19F, 20.5 2.8 NH2 NH2 R22T, K26R NV1G1137 NV1D2974 129 Y1Q, W7Q, S11A, M19F, V20S, 21.6 1.34 (synthetic) R22T NV1G1221 NV1D3017 140 Y1Q, W7Q, S11A, E12R, M19F, 21.9 2.48 R22T NV1G1722 NV1D3533 273 Y1Q, W7Q, S11A, E12K, M19F, 22.4 3.5 V20S, R22T, K26R NV1G1767 NV1D3345 177 Y1Q, Q3S, W7Q, S11R, M19F, 22.4 2.52 R22T, K26R NV1G1769 NV1D3346 178 Y1Q, K4R, W7Q, S11R, M19F, 23.2 3.39 R22T, K26R NV1G1780 NV1D3387 216 Y1Q, W7Q, S11R, E17D, M19F, 23.7 2.85 R22T, K26R NV1G1886 NV1D3249 162 Y1Q, W7Q, S11A, M19F 24.1 11.5 NV1G1812 NV1D3382 211 Y1Q, W7Q, S11R, K14S, M19F, 24.3 2.14 R22T, K26R NV1G1857 NV1D3366 196 Y1Q, W7Q, D10S, S11R, M19F, 24.6 3.8 R22T, K26R NV1G1821 NV1D3378 207 Y1Q, W7Q, S11R, K14A, M19F, 24.8 2.66 R22T, K26R NV1G1993 NV1D3792 335 Y1Q, W7Q, S11R, M19F, R22T, 25.3 2.8 K26R NV1G1007 NV1D2775 56 Y1Q, W7Q, S11A, M19F 25.4 2 NV1G1787 NV1D3396 224 Y1Q, W7Q, S11R, G18Q, M19F, 26.4 3.17 R22T, K26R NV1G1257 NV1D3016 139 Y1Q, W7Q, S11A, E12N, M19F, 26.6 3.1 R22T NV1G1153 NV1D3034 116 Y1Q, W7Q, S11R, M19F, R22T, 27.3 2.02 (synthetic) K26R NV1G1803 NV1D3403 230 Y1Q, W7Q, S11R, M19F, R22T, 28.3 1.97 K26R, K27A (-GP) N-Ac- N-Ac- 115 Y1Q, W7Q, S11A, M19F, V20S, 28.6 2.23 NV1G1137 NV1D2974 R22T NV1G1531 NV1D3019 142 Y1Q, W7Q, S11A, E12R, M19F, 28.7 4.78 K26R NV1G1513 NV1D3007 134 Y1Q, W7Q, S11A, M19F, K26R 29.6 9.17 NV1G1991 NV1D3789 333 Y1Q, W7Q, S11R, M19F, R22T, 29.9 5.19 K26R NV1G1013 NV1D2733 40 Y1R, W7Q, M19F 7.54 2.9 NV1G1740 NV1D3580 318 Y1R, W7Q, S11A, E12R, M19F, 8.4 1.5 V20S NV1G1757 NV1D3538 278 Y1R, W7Q, S11R, E12N, M19F, 11.6 1.4 R22T, K26R NV1G1741 NV1D3569 307 Y1R, W7Q, S11A, E12R, M19F, 11.9 0.8 R22T NV1G1715 NV1D3584 322 Y1R, W7Q, S11A, E12N, M19F, 13.9 1.4 V20S NV1G1754 NV1D3529 269 Y1R, W7Q, S11A, E12K, M19F, 14.6 1.7 R22T, K26R NV1G1005 NV1D2772 59 Y1R, W7Q, S11A, M19F 15.6 1.8 NV1G1733 NV1D3577 315 Y1R, W7Q, S11A, M19F, V20S 18.8 2.2 NV1G1744 NV1D3534 274 Y1R, W7Q, S11A, E12K, M19F, 20.6 2.2 V20S, R22T, K26R NV1G1724 NV1D3562 301 Y1R, W7Q, S11A, E12R, M19F, 23.6 2.7 V20S, R22T NV1G1735 NV1D3566 305 Y1R, W7Q, S11A, M19F, R22T 23.7 2.5 NV1G1760 NV1D3543 283 Y1R, W7Q, S11R, E12N, M19F, 23.8 1.9 V20S, R22T, K26R NV1G1759 NV1D3547 287 Y1R, W7Q, S11R, M19F, R22T, 26.5 2.1 K26R NV1G1751 NV1D3558 297 Y1R, W7Q, S11A, E12N, M19F, 26.7 3.4 V20S, R22T NV1G1726 NV1D3551 291 Y1R, W7Q, S11R, M19F, V20S, 29.3 3.8 R22T, K26R NV1G1105 NV1D2729 39 Y1R, W7Q, S11A 8 8.85E−01 NV1G957 NV1D2668 23 Y1R, W7Q 17.5 2.6 (-GP) (-GP) 109 Y1S, W7Q, S11A, M19F 9.47 1.28 NV1G1001 NV1D2773 (-GP) (-GP) 110 Y1S, W7Q, S11A, M19F 11.5 0.61 NV1G1001- NV1D2773- NH-methyl NH-methyl NV1G1003 NV1D2734 44 Y1S, W7Q, M19F 13.4 0.8 NV1G1864 NV1D3581 319 Y1S, W7Q, S11A, E12R, M19F, 14.6 1.7 V20S NV1G1748 NV1D3530 270 Y1S, W7Q, S11A, E12K, M19F, 15.6 2.2 R22T, K26R NV1G1758 NV1D3548 288 Y1S, W7Q, S11R, M19F, R22T, 17.6 1.9 K26R NV1G1727 NV1D3544 284 Y1S, W7Q, S11R, E12N, M19F, 17.8 2.2 V20S, R22T, K26R NV1G1719 NV1D3570 308 Y1S, W7Q, S11A, E12R, M19F, 18.1 1.5 R22T NV1G1742 NV1D3535 275 Y1S, W7Q, S11A, E12K, M19F, 18.7 2.8 V20S, R22T, K26R NV1G1001 NV1D2773 65 Y1S, W7Q, S11A, M19F 18.8 1.5 NV1G1753 NV1D3585 323 Y1S, W7Q, S11A, E12N, M19F, 19.4 2.1 V20S NV1G1762 NV1D3539 279 Y1S, W7Q, S11R, E12N, M19F, 19.4 1.8 R22T, K26R NV1G1755 NV1D3574 312 Y1S, W7Q, S11A, E12N, M19F, 22.3 2.7 R22T NV1G1717 NV1D3563 302 Y1S, W7Q, S11A, E12R, M19F, 22.4 2.4 V20S, R22T NV1G1866 NV1D3559 298 Y1S, W7Q, S11A, E12N, M19F, 26.5 5.02 V20S, R22T NV1G1721 NV1D3552 292 Y1S, W7Q, S11R, M19F, V20S, 28.1 3.7 R22T, K26R NV1G975 NV1D2669 26 Y1S, W7Q 18.4 5.7 NV1G983 NV1D2730 43 Y1S, W7Q, S11A 25.5 4.3 NV1G1750- NV1D3586- 325 W7Q, S11A, E12N, M19F, V20S 4.23 0.33 NH2 NH2 NV1G1747 NV1D3531 271 W7Q, S11A, E12K, M19F, R22T, 13 2.1 K26R NV1G1763 NV1D3540 280 W7Q, S11R, E12N, M19F, R22T, 16 1.5 K26R NV1G1739 NV1D3582 320 W7Q, S11A, E12R, M19F, V20S 17.8 2.2 NV1G1750 NV1D3586 324 W7Q, S11A, E12N, M19F, V20S 20.5 2.2 NV1G1718 NV1D3571 309 W7Q, S11A, E12R, M19F, R22T 21 2.3 NV1G1865 NV1D3560 299 W7Q, S11A, E12N, M19F, V20S, 27.2 3.42 R22T NV1G1766 NV1D3549 289 W7Q, S11R, M19F, R22T, K26R 27.5 3.2 NV1G961 NV1D2676 29 W7Q, S11A 26.5 2.9 NV1G951 NV1D2674 18 Y1A, S11A 4.03 0.2 NV1G1011 NV1D2740 37 Y1Q, S11A, M19F 3.62 9.9 NV1G977 NV1D2665 22 Y1Q, M19F 4.9 0.4 NV1G949 NV1D2675 21 Y1Q, S11A 4.33 0.3 NV1G973 NV1D2662 25 Y1R, M19F 4.03 0.4 NV1G965 NV1D2672 24 Y1R, S11A 4.5 0.3 NV1G1009 NV1D2738 45 Y1S, S11A, M19F 2.57 0.2 NV1G995 NV1D2663 28 Y1S, M19F 4.19 0.4 NV1G1107- NV1D2890- 112 Y1S, M6F, S11A, M19L 9.12 1.17 NH2 NH2 NV1G971 NV1D2673 27 Y1S, S11A 4.31 0.5 NV1G1782 NV1D3383 212 Y1Q, W7Q, S11R, E17R, M19F, 30.3 4.06 R22T, K26R, NV1G1990 NV1D3788 332 Y1Q, W7Q, S11R, M19F, R22T, 30.3 4.78 K26R, (-GP) N-Ac- (-GP) N-Ac- 120 Y1Q, W7Q, S11R, M19F, R22T, 30.4 2.96 NV1G1153- NV1D3034 K26R NV1G1786 NV1D3389 218 Y1Q, W7Q, S11R, E17S, M19F, 30.8 4.48 R22T, K26R, NV1G1147 NV1D2969 124 Y1S, W7Q, S11A, M19F, V20S 31 6.15 NV1G1764 NV1D3554 294 Y1A, W7Q, S11R, M19F, V20S, 31.4 3.3 R22T, K26R NV1G963 NV1D2671 20 Y1Q, W7Q 31.5 6.4 NV1G1835 NV1D3379 208 Y1Q, K4D, W7Q, S11R, M19F, 31.6 2.88 R22T, K26R NV1G1231 NV1D3035 148 Y1Q, W7Q, S11A, E12N, M19F, 32 4.9 R22T, K26R NV1G1743 NV1D3564 303 W7Q, S11A, E12R, M19F, V20S, 32.3 3.1 R22T NV1G1960 NV1D3803 345 Y1Q, W7Q, S11R, M19F, R22T, 32.3 5.33 K26R NV1G1924 NV1D3470 250 Y1Q, W7Q, S11R, M19L, R22T, 32.5 403 K26R NV1G1756 NV1D3575 313 W7Q, S11A, E12N, M19F, R22T 33.2 3.9 NV1G1109 NV1D2899 67 Y1S, W7Q, S11A, M19L 33.3 6.7 NV1G1818 NV1D3368 122 Y1Q, W7Q, S11R, E12T, M19F, 33.5 10.7 R22T, K26R NV1G1784 NV1D3386 215 Y1Q, W7Q, S11R, E17A, M19F, 33.6 4.71 R22T, K26R NV1G1141 NV1D2972 127 Y1Q, W7Q, S11A, M19F, V20S 34.1 6.2 NV1G1774 NV1D3347 179 Y1Q, K4T, W7Q, S11R, M19F, 34.2 5.99 R22T, K26R NV1G1881 NV1D3257 167 Y1Q, W7Q, S11A, M19F 34.2 2.81 NV1G1915 NV1D3467 249 Y1Q, W7Q, S11R, E17G, M19F, 34.5 4 R22T, K26R NV1G1984 NV1D3806 348 Y1Q, W7Q, S11R, M19F, R22T, 35.1 4.56 K26R NV1G1716 NV1D3561 300 Y1A, W7Q, S11A, E12N, M19F, 35.6 5 V20S, R22T, NV1G1255 NV1D3014 137 Y1Q, W7Q, S11R, M19F, R22T 36.1 5.37 NV1G1959 NV1D3818 357 Y1Q, W7Q, S11R, M19F, R22T, 36.3 204 K26R NV1G1825 NV1D3377 206 Y1Q, W7Q, S11R, K14T, M19F, 36.4 4.83 R22T, K26R NV1G1723 NV1D3536 276 W7Q, S11A, E12K, M19F, V20S, 37 5.4 R22T, K26R NV1G1732 NV1D3555 295 Y1R, W7Q, S11A, M19F, V20S, 37.4 4.3 R22T, NV1G1983 NV1D3809 350 Y1Q, W7Q, S11R, M19F, R22T, 38.9 4.81 K26R NV1G1982 NV1D3805 347 Y1Q, W7Q, S11R, M19F, R22T, 41.2 5.44 K26R NV1G1785 NV1D3385 214 Y1Q, W7Q, S11R, E17T, M19F, 41.5 6.5 R22T, K26R NV1G1583 NV1D3030 144 Y1Q, W7Q, S11R, E12N, M19F, 41.9 5.15 R22T NV1G1729 NV1D3545 285 W7Q, S11R, E12N, M19F, V20S, 42.8 4.6 R22T, K26R NV1G1007 NV1D2775 56 Y1Q, W7Q, S11A, M19F 42.9 6.7 NV1G1734 NV1D3568 306 Q1A, W7Q, S11A, M19F, R22T 44 8.3 NV1G1683 NV1D3523 263 Y1Q, W7Q, S11R, M19F, R22T, 44.7 K26R NV1G1834 NV1D3360 191 Y1Q, W7Q, D10R, S11R, M19F, 45.2 3.79 R22T, K26R NV1G1795 NV1D3401 229 Y1Q, W7Q, S11R, M19F, R22T, 45.5 6.58 K26R, K27R NV1G1689 NV1D3514 255 Y1Q, W7Q, S11R, M19F, R22T, 46.4 K26R NV1G2043 NV1D3835 370 Y1Q, W7Q, S11R, M19F, R22T, 46.4 4.09 K26R NV1G1783 NV1D3384 213 Y1Q, W7Q, S11R, E17K, M19F, 46.8 7.39 R22T, K26R NV1G1239 NV1D3020 143 Y1Q, W7Q, S11A, M19F, R22T, 47.2 7.84 K26R NV1G1788 NV1D3399 227 Y1Q, W7Q, S11R, M19F, V20T, 47.3 6.36 R22T, K26R NV1G899 NV1D2774 52 Y1A, W7Q, S11A, M19F 50.5 15.2 NV1G2057 NV1D3799 341 Y1Q, W7Q, S11R, M19F, R22T, 50.6 6.33 K26R NV1G1738 NV1D3578 316 W7Q, S11A, M19F, V20S, 50.7 5.7 NV1G1713 NV1D3525 265 Y1Q, W7Q, S11R, M19F, R22T, 52.3 K26R NV1G1765 NV1D3553 293 W7Q, S11R, M19F, V20S, R22T, 52.4 10 K26R NV1G1916 NV1D3465 247 Y1Q, W5F, W7Q, S11R, M19F, 52.8 10.3 R22T, K26R NV1G1977 NV1D3804 346 Y1Q, W7Q, S11R, M19F, R22T, 53.6 6.27 K26R NV1G1879 NV1D3259 168 Y1Q, W7Q, S11A, M19F 54.9 7.62 NV1G1884 NV1D3256 166 Y1Q, W7Q, S11A, M19F 55.7 10.5 NV1G1986 NV1D3819 358 Y1Q, W7Q, S11R, M19F, R22T, 56 6.57 K26R NV1G1633 NV1D3251 163 Y1Q, W7Q, S11A, M19F 56.1 13.9 NV1G1880 NV1D3261 170 Y1Q, W7Q, S11A, M19F 57 6.25 NV1G1985 NV1D3808 349 Y1Q, W7Q, S11R, M19F, R22T, 57 6.74 K26R NV1G1849 NV1D3400 228 Y1Q, W7Q, S11R, M19F, V20Q, 57.3 9.52 R22T, K26R NV1G1883 NV1D3260 169 Y1Q, W7Q, S11A, M19F 57.6 6.91 NV1G1145 NV1D2970 125 Y1S, W7Q, S11A, M19F, R22T 58 18.8 NV1G1697 NV1D3517 258 Y1Q, W7Q, S11R, M19F, R22T, 58.5 K26R NV1G1737 NV1D3579 317 Y1A, W7Q, S11A, M19F, V20S 59.9 9.6 NV1G1978 NV1D3833 368 Y1Q, W7Q, S11R, M19F, R22T, 60.3 9.57 K26R NV1G1954 NV1D3800 342 Y1Q, W7Q, S11R, M19F, R22T, 60.9 6.43 K26R NV1G1989 NV1D3791 334 Y1Q, W7Q, S11R, M19F, R22T, 61.8 8.66 K26R NV1G1815 NV1D3380 209 Y1Q, K4E, W7Q, S11R, M19F, 64 10.5 R22T, K26R NV1G1967 NV1D3793 336 Y1Q, W7Q, S11R, M19F, R22T, 64.6 8.19 K26R NV1G1869 NV1D3573 311 Y1R, W7Q, S11A, E12N, M19F, 64.7 50.7 R22T NV1G1872 NV1D3777 330 Y1Q, W7Q, S11R, M19F, R22T, 64.9 15.3 K26R NV1G1979 NV1D3834 369 Y1Q, W7Q, S11R, M19F, R22T, 65.5 7.59 K26R NV1G1827 NV1D3365 195 Y1Q, W7Q, D10Q, S11R, M19F, 66.1 10.1 R22T, K26R NV1G1768 NV1D3341 174 Y1Q, Q3T, W7Q, S11R, M19F, 66.2 9.32 R22T, K26R NV1G911 NV1D2666 30 W7Q, M19F 66.5 36.7 NV1G1856 NV1D3397 225 Y1Q, W7Q, S11R, G18S, M19F, 66.7 7.31 R22T, K26R NV1G1973 NV1D3810 351 Y1Q, W7Q, S11R, M19F, R22T, 66.9 7.04 K26R NV1G1855 NV1D3398 226 Y1Q, W7Q, S11R, M19F, V20S, 67.3 11 R22T, K26R NV1G1961 NV1D3802 344 Y1Q, W7Q, S11R, M19F, R22T, 68 8.23 K26R NV1G1846 NV1D3431 244 Y1Q, K4E, W7Q, S11R, E17K, 68.6 13.9 M19F, R22T, K26R NV1G1771 NV1D3348 180 Y1Q, K4A, W7Q, S11R, M19F, 70.6 15.9 R22T, K26R NV1G1691 NV1D3520 261 Y1Q, W7Q, S11R, M19F, R22T, 71.4 K26R NV1G1681 NV1D3511 252 Y1Q, W7Q, S11R, M19F, R22T, 71.5 K26R NV1G1968 NV1D3822 359 Y1Q, W7Q, S11R, M19F, R22T, 74.2 11.1 K26R NV1G1813 NV1D3424 238 Y1Q, W7Q, D10K, S11R, E12K, 75.2 12.2 M19F, R22T, K26R NV1G1067 NV1D2893 57 Y1Q, W7Q, S11A, M19L 75.5 10.5 NV1G1867 NV1D3546 286 Y1A, W7Q, S11R, E12N, M19F, 76 17.6 V20S, R22T, K26R NV1G1143 NV1D2971 126 Y1S, W7Q, S11A, M19F, V20S, 77.5 22.1 R22T NV1G1806 NV1D3409 232 Y1Q, W7Q, S11R, M19F, R22T, 79.1 11.3 K26R, K28T NV1G1061 NV1D2896 60 Y1R, W7Q, S11A, M19L 80.3 7.13 NV1G1793 NV1D3419 236 Y1Q, W7Q, S11R, M19F, R22T, 80.9 11.9 K26R, W30D NV1G1613 NV1D3057 157 Y1Q, W7Q, S11R, E12K, M19F, 83.4 16.6 K26R NV1G1585 NV1D3052 155 Y1Q, W7Q, S11A, E12K, M19F, 84.8 28.8 K26R NV1G1707 NV1D3524 264 Y1Q, W7Q, S11R, M19F, R22T, 84.9 K26R NV1G1773 NV1D3350 182 Y1Q, K4E, W7Q, S11R, M19F, 85.6 14.4 R22T, K26R NV1G1949 NV1D3828 364 Y1Q, W7Q, S11R, M19F, R22T, 87.5 11 K26R NV1G1976 NV1D3811 352 Y1Q, W7Q, S11R, M19F, R22T, 87.7 15.7 K26R NV1G1956 NV1D3801 343 Y1Q, W7Q, S11R, M19F, R22T, 88.1 11.4 K26R NV1G1975 NV1D3832 367 Y1Q, W7Q, S11R, M19F, R22T, 88.4 12.3 K26R NV1G1839 NV1D3774 328 Y1Q, W7Q, S11R, M19F, R22T, 88.6 19.6 K26R NV1G1971 NV1D3830 366 Y1Q, W7Q, S11R, M19F, R22T, 88.6 9.88 K26R NV1G1882 NV1D3262 171 Y1Q, W7Q, S11A, M19F 89.2 8.32 NV1G1950 NV1D3797 339 Y1Q, W7Q, S11R, M19F, R22T, 91.1 13.5 K26R NV1G1828 NV1D3363 194 Y1Q, W7Q, D10A, S11R, M19F, 93.1 15.3 R22T, K26R NV1G1139 NV1D2973 128 Y1Q, W7Q, S11A, M19F, R22T 93.9 19.5 NV1G1842 NV1D3430 243 Y1Q, K4D, W7Q, S11R, E17K, 93.9 14.1 M19F, R22T, K26R NV1G1948 NV1D3798 340 Y1Q, W7Q, S11R, M19F, R22T, 94.5 17.8 K26R NV1G1807 NV1D3408 231 Y1Q, W7Q, S11R, M19F, R22T, 94.8 17.8 K26R, K28R NV1G1137 NV1D2974 129 Y1Q, W7Q, S11A, M19F, V20S, 95.7 16.2 R22T NV1G1843 NV1D3432 245 Y1Q, K4E, W7Q, S11R, E17R, 95.9 10.4 M19F, R22T, K26R NV1G1822 NV1D3423 237 Y1Q, W7Q, D10R, S11R, E12R, 99.5 9.45 M19F, R22T, K26R NV1G1862 NV1D3556 296 W7Q, S11A, M19F, V20S, R22T 100 18.5 NV1G1969 NV1D3795 337 Y1Q, W7Q, S11R, M19F, R22T, 100 14.5 K26R NV1G1980 NV1D3812 353 Y1Q, W7Q, S11R, M19F, R22T, 101 23.6 K26R NV1G1850 NV1D3414 235 Y1Q, W7Q, S11R, M19F, R22T, 102 19.4 K26R, K28S NV1G1981 NV1D3815 356 Y1Q, W7Q, S11R, M19F, R22T, 102 13.5 K26R NV1G1851 NV1D3390 219 Y1Q, W7Q, S11R, G18R, M19F, 108 15.5 R22T, K26R NV1G1922 NV1D3466 248 Y1Q, W7Q, S11E, M19F, R22T, 108 922 K26R NV1G1778 NV1D3349 181 Y1Q, K4D, W7Q, S11R, M19F, 109 16 R22T, K26R NV1G1972 NV1D3824 361 Y1Q, W7Q, S11R, M19F, R22T, 110 16.1 K26R NV1G1974 NV1D3796 338 Y1Q, W7Q, S11R, M19F, R22T, 110 19.6 K26R NV1G1826 NV1D3357 188 Y1Q, W7Q, T8E, S11R, M19F, 111 15.1 R22T, K26R NV1G1892 NV1D3439 246 Y1Q, W7Q, S11R, M19F, R22T, 112 13.2 K26R, W30G NV1G1819 NV1D3375 204 Y1Q, W7Q, S11R, R13S, M19F, 113 1270 R22T, K26R NV1G1805 NV1D3410 233 Y1Q, W7Q, S11R, M19F, R22T, 114 21.5 K26R, K28A NV1G1831 NV1D3374 203 Y1Q, W7Q, S11R, R13Q, M19F, 114 1600 R22T, K26R NV1G1693 NV1D3512 253 Y1Q, W7Q, S11R, M19F, R22T, 115.6 K26R NV1G1854 NV1D3392 221 Y1Q, W7Q, S11R, G18T, M19F, 117 21.8 R22T, K26R NV1G1951 NV1D3829 365 Y1Q, W7Q, S11R, M19F, R22T, 122 13.3 K26R NV1G1860 NV1D3393 222 Y1Q, W7Q, S11R, G18A, M19F, 125 24.8 R22T, K26R NV1G1099 NV1D2732 36 Y1Q, W7Q, S11A 126 26.9 NV1G1705 NV1D3513 254 Y1Q, W7Q, S11R, M19F, R22T, 131.2 K26R NV1G1848 NV1D3426 240 Y1Q, W7Q, D10K, S11R, E12K, 135 39.9 R13D, M19F, R22T, K26R NV1G1952 NV1D3813 354 Y1Q, W7Q, S11R, M19F, R22T, 139 30.1 K26R NV1G1631 NV1D3252 164 Y1Q, W7Q, S11A, M19F 145 53 NV1G1817 NV1D3371 201 Y1Q, W7Q, S11R, R13A, M19F, 151 33.7 R22T, K26R NV1G1789 NV1D3394 223 Y1Q, W7Q, S11R, G18D, M19F, 155 41.4 R22T, K26R NV1G1852 NV1D3391 220 Y1Q, W7Q, S11R, G18K, M19F, 157 23.1 R22T, K26R NV1G1709 NV1D3510 251 Y1Q, W7Q, S11R, M19F, R22T, 159 K26R NV1G1840 NV1D3425 239 Y1Q, W7Q, D10R, S11R, E12R, 161 27.9 R13D, M19F, R22T, K26R NV1G1809 NV1D3413 234 Y1Q, W7Q, S11R, M19F, R22T, 164 43.7 K26R, K28Q NV1G1863 NV1D3356 187 Y1Q, W7Q, T8D, S11R, M19F, 167 32.2 R22T, K26R NV1G1699 NV1D3527 267 Y1Q, W7Q, S11R, M19F, R22T, 169.1 K26R NV1G1844 NV1D3428 242 Y1Q, W7Q, D10K, S11R, E12K, 180 52.4 R13E, M19F, R22T, K26R NV1G1853 NV1D3370 200 Y1Q, W7Q, S11R, R13T, M19F, 181 25.1 R22T, K26R NV1G1946 NV1D3825 362 Y1Q, W7Q, S11R, M19F, R22T, 194 28.4 K26R

The wild-type Protoxin-II inhibits Nav1.7 with an IC₅₀ value of about 4 nM in veratridine-induced depolarization inhibition assay as described in Example 3. Variants retaining significant Nav1.7 potency were characterized further. FIG. 1 shows the sequence genus of generated Protoxin-Ill variants that inhibit Nav1.7 with an IC₅₀ value of 30 nM or less.

Select Protoxin-II variants were tested for their inhibition of Nav1.7 and for their selectivity against human Nav1.6 using QPatch. IC₅₀ values for both Nav1.7 and Nav1.6 for select peptides obtained using QPatch are shown in FIGS. 2A and 2B. These peptides inhibited Nav1.7 with an IC₅₀ of 30 nM or less, and were at least 30-fold selective over Nav1.7 when compared to Nav1.6.

The amino acid sequences of the peptides shown in FIGS. 2A and 3B are shown in FIGS. 3A-3C. All these peptides had W7Q and M19F substitutions when compared to the wild type Protoxin-II.

The Protoxin-II variants were expressed and purified as described in Example 1, or synthesized by standard solid phase synthesis methods. The yields of the recombinant or synthetic peptides were compared to the yields of the wild-type Protoxin-II. Table 12 shows that the yields of the select Protoxin-II variants were significantly higher than that of Protoxin-II, indicating improved folding properties of the variants. The scale of the solid-phase synthesis was 0.5 mmol.

TABLE 12 Solid phase synthesis Yield Yield Recombinant Total from From expression Peptide yield Crude Linear % active isomer Protoxin-II 52 mg 2.7% 7.3% 54.0% NV1D2775 84 mg 4.5% 18.7% 89.1% NV1D3034 149 mg  8.0% 21.0% 85.2% NV1D3368 83 mg 4.0% 24.0% 93.8%

Example 5. Protoxin-II Variants are Efficacious in In Vivo Models of Pain

Materials and Methods

Animals Male C57B1/6 mice (24-26 g), ordered from Charles River and housed individually, were used for this study.

Behavioral Tests

Von Frey Test:

Mechanical (tactile) threshold was assessed by Von Frey Hairs following the Up-Down method (Dixon, 1980, Chaplan et al., 1994). 7 graded stimuli (von Frey filaments: 0.03, 0.07, 0.16, 0.4, 0.6, 1, 2 g; Stoelting, Wood Dale, Ill.) were used. Von Frey hairs were presented perpendicularly against the center plantar area (between toris) on a hindpaw. Sufficient force was applied to bend the filament slightly and held for 3 seconds. Per the Chaplan paper, a positive response can be either 1) a sharp withdrawal or 2) immediate flinching upon removal of the filament. See Chaplan et al for more details. Mice were acclimated to the wire mesh in the testing chamber for 30-60 minutes prior to testing.

Hargreaves Test:

A modified Hargreaves box was used to measure thermal paw withdrawal latency (PWL) (Hargreaves et al., 1988, Pain, 32:77-88; Dirig et al., 1997, J Neurosci. Methods, 76:183-191). This box consists of a chamber with a raised glass floor maintained at a constant temperature (27° C.). The thermal nociceptive stimulus originates from a projection bulb light beam below the glass surface. The light beam is aimed at the area between toris (center plantar). The “start” button will turn on the light and start the timer. Movements (such as a sudden withdrawal) of the stimulated paw will trigger the switch to turn off the light and stop the timer. The latency in seconds is displayed. If no movement occurs, the bulb will be turned off after 20 seconds (cutoff) to prevent tissue injury. The animals were allowed to habituate on the glass surface for 30-60 minutes before PWL measurement. Constant amperage was used throughout the study, which resulted in Pre-test paw withdrawal latencies between 8-12 seconds when averaged over 3 to 6 read-outs taken at least 5 minutes apart.

MPE % Calculation:

Percent maximum possible effect (MPE %)=(T₁−T₀)/(Tc−T₀)×100%. T₀: threshold on day0 (post-CFA, pre-pump); T₁: threshold on day1 post pump implantation; Tc: cut-off of the test (20 s for the Hargreaves test and 2 g for the Von Frey test)

Hotplate Test:

Animals were placed on a 10″×10″ metal plate surrounded by 4 Plexiglas walls (15 inches high). The plate was maintained at a temperature of either 50 or 55° C. The response latency (time when the animal first flinches or licks its hind paw, jumps, or vocalizes) was measured and the animal removed from the plate. Animals showing no response were removed from the plate after 40 s (50° C.) or 20 s (55° C.) to prevent any possible tissue damage. This trial was repeated 2-5 times every 15-60 minutes in a day.

Inflammatory Pain Models

CFA Model:

Animals were anesthetized with isoflurane (4% induction and 2% maintenance) and 20 μL of 100% Complete Freund's Adjuvant (CFA; Sigma-Aldrich; Saint Louis, Mo.) was injected into the center plantar area on one hind paw using a 27 gauge needle attached to a 50 μL Hamilton syringe. Carrageenan model: Animals were anesthetized with isoflurane (4% induction and 2% maintenance) and 25 μL of 2% λ-carrageenan (Sigma-Aldrich; Saint Louis, Mo.) dissolved in normal saline was injected into the center plantar area on hind paws using an insulin syringe (BD; Franklin Lakes, N.J.).

Implantation of Mini Pumps Alzet micro-osmotic mini pumps (Durect Corporation Model 1003D and 2001D) were filled and primed per manufacturer's guide. Mice were anesthetized with isoflurane (5% induction; 2% maintenance). Their backs were shaved, wiped down with isopropyl alcohol and povidone iodine, and a small incision was made between the scapulae. Using a pair of forceps or hemostat, a small pocket was formed by spreading the subcutaneous connective tissues apart. The pump was inserted into the pocket with the flow moderator pointing away from the incision. The skin incision was then closed using 7 mm staples and the animals were allowed to recover in their home cages. Data Analysis Data are represented as mean±s.e.m. Prism (Graphpad Software Inc., La Jolla, Calif.) was used for graphing and statistical analysis. For comparison of threshold values over time, a two-way ANOVA followed by Bonferroni's multiple comparison test was used with a significance level of p<0.05. Hotplate and MPE % data were analyzed by one-way ANOVA followed by Bonferroni's multiple comparison test. Results

Efficacy of variants NV1D3034-OH (NV1D3034-COOH), NV1D3368-OH (NV1D3368-COOH) and NV1D2775-OH (NV1D2775-COOH) was studied in the CFA model, a commonly used model of inflammatory pain. The injection of CFA in the hindpaw induced paw edema (not shown) and hypersensitivity to thermal stimuli (thermal hyperalgesia), as indicated by the lowered thermal latency in the injected paw on day0 (FIG. 6A). Thermal hyperalgesia was completely reversed by NV1D3034-OH at 684 and 1824 μg/day, when administered by a subcutaneous osmotic mini-pump (FIGS. 4A and 4B).

NV1D3368-OH fully reversed CFA-induced thermal hyperalgesia at 684 and 1824 μg/day (FIGS. 5A and 5B). NV1D2775-OH demonstrated strong efficacy in the CFA model. Thermal latencies reached values close to the cut-off following NV1D2775 administration (FIGS. 6A and 6B, 1824 μg/day), suggesting a strong analgesia effect on top of the anti-hyperalgesia effect. In addition, NV1D2775-OH reversed CFA-induced tactile allodynia (FIGS. 6C and 6D, 1824 μg/day). The anti-hyperalgesic effect of NV1D2775-OH was seen as early as 4 hr post-pump implantation (FIG. 7A). The effect reached the maximum at 8 hr in both the thermal and tactile tests (FIGS. 7A and 7B), which was maintained at 24 hr. Thermal latency and tactile threshold returned the control level by 48 h post pump implantation (approximately 24 h after the pumps were predicted to be empty) (FIGS. 7A and 7B).

CFA-induced thermal hyperalgesia was readily reversed by two additional peptides, NV1D3368-amide (NV1D3368-NH₂) and NV1D3034-N-methylamide (NV1D3034-NHMe). Thermal MPE % from the experiments is summarized in Table 13.

TABLE 13 Dose (μg/day/mouse) Peptide Vehicle (PBS) 228 684 1824 NV1D3034-OH 20 ± 7 (11) 22 ± 6 (6) 48 ± 10* (8) 50 ± 6* (8) NV1D3368-OH 13 ± 7 (8) 23 ± 8 (7) 42 ± 9* (7) 47 ± 6** (8) NV1D2775-OH 15 ± 4 (20) 35 ± 8 (8) 57 ± 12*** (8) 85 ± 6**** (12) NV1D3368-NH₂ 15 ± 13 (6) 27 ± 4 (4) 46 ± 9 (4) 55 ± 15 (6) NV1D3034-NHMe 5 ± 25 (3) 49 ± 17 (6) *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001 vs. PBS, one-way ANOVA followed by Bonferroni's multiple comparison.

NV1D2775-OH also exhibited strong, dose-dependent efficacy in the hotplate test (FIG. 8). Latencies at 50 and 55° C. reached values near cut-off following the administration of 1824 μg/day. At 228 μg/day, NV1D2775-OH produced a modest yet significant increase in the thermal latency, compared to the PBS control.

The efficacy of NV1D2775-OH was evaluated in another model of inflammatory pain, the carrageenan model. Animals were implanted with NV1D2775-OH or PBS pumps. Thermal withdrawal latencies were measured pre- and on day1 post-pump. λ-carrageenan was injected into the hindpaws and thermal latencies were measured again on 2, 3 and 4 hr following carrageenan. NV1D2775-OH at 1824 μg/day produced significant analgesia (FIG. 9). Injection of λ-carrageenan in the hindpaws induced inflammation (not shown) and lowered thermal paw withdrawal latency in the Hargreaves test over the 4 hr test-period (FIG. 9, PBS group). Animals pretreated with NV1D2775-OH at 1824 μg/day were fully protected from carrageenan-induced hyperalgesia.

Example 6. Generation and Characterization of Combinatorial Protoxin-II Variants

An amino acid scanning library was generated for Protoxin-II. At every non-cysteine position in Protoxin-II (Tyr1, Gln3, Lys4, Trp5, Met6, Trp7, Thr8, Asp10, Ser11, Glu12, Arg13, Lys14, Glu17, Gly18, Met19, Val20, Arg22, Leu23, Trp24, Lys26, Lys27, Lys28, Leu29 and Trp30) the following residues were substituted in place of the native residue: Ala, Asp, Glu, Phe, Gly, His, Ile, Lys, Leu, Asn, Pro, Gln, Arg, Ser, Thr, Val, and Tyr.

Mutant peptides were expressed as recombinant fusions to human serum albumin and site-specifically enzymatically cleaved using HRV3C to generate Protoxin-II variants as described in Example 1. Each Protoxin-II variant, after cleavage from HSA had a residual N-terminal GP from the cleavage site. For each Protoxin-Ill variant, IC₅₀ values against human Nav1.7 were measured using veratridine-induced depolarization inhibition or Qpatch according to the protocols described in Example 3. Variants demonstrating IC₅₀≤0:100 nM for human Nav1.7 were counter-screened for selectivity against additional hNav channels using Qpatch electrophysiology. Selective hits were identified and used in the design of combinatorial peptide libraries which were produced using both recombinant expression and solid-phase peptide synthesis. Combinatorial variants were screened using the same strategy as detailed above.

Based on the results, positions that can be mutated to improve selectivity include Gln3, Ser11, Glu12, Lys14, Glu17, Gly18, Leu29 and Trp30 (residues numbering according to SEQ ID NO: 1).

The solution structure of Protoxin-II was determined by NMR and is shown in FIG. 10 as a surface representation. The left hand side of the Figure shows the previously described (Park et al., J. Med. Chem. 2014, 57:6623-6631) ring of Trp residues, W5/W7/W24, surrounding M6. On the opposite side of the molecule, using both mutagenesis and the NMR structure, a selectivity face was identified in this study on Protoxin-II consisting of multiple amino acid positions which can be mutated to improve selectivity for hNav1.7 over other sodium channel isoforms. The residues residing on the selectivity face include residues Ser11, Glu12, Lys14, Glu17, Gly18, Leu29 and Trp30 (residue numbering according to SEQ ID NO: 1). The identification of the selectivity face and multiple positions within responsible for selectivity towards Nav1.7 has not been described earlier.

Improved selectivity of Protoxin II variants with substitution at Ser11 is unexpected as it has been earlier demonstrated that mutation of Ser11 affect activity on multiple Nav channels, and therefore the residue was concluded not to play a role in Protoxin-II Nav1.7 selectivity (Park et al., J. Med. Chem. 2014, 57:6623-6631).

A key step in the synthetic production of Protoxin-II variants is the oxidative refolding of the linear peptide, where the disulfide pairings are formed. The RP-HPLC trace for native Protoxin-II purification following refolding revealed multiple peaks at differing retention times that were of correct mass but demonstrated differing levels of activity, indicative of a mixture of properly and improperly folded isomers of the peptide.

The relative abundance of the RP-HPLC major peak, and therefore the relative abundance of correctly folded peptide could be improved by making substitutions at various Protoxin-II positions. Mutation of Trp7 or Trp30 improved folding of the resulting Protoxin-II variant. Mutation of both Trp7 and Trp30 in combination further improved folding of the resulting Protoxin-II variant, and could rescue folding of difficult-to-refold Protoxin-II variants.

Production of combinatorial mutant peptides having one or more substitutions that improved selectivity (Gln3, Ser11, Glu12, Lys14, Glu17, Gly18, and Leu29) as well as mutations at Trp7 and Trp30 resulted in peptides with both improved selectivity and improved refolding properties. Protoxin-II belongs to a family 3 of inhibitory cysteine knot peptides (Klint et. al., Toxicon 60:478-491, 2012). Trp7 is conserved in all family 3 members, and substitutions at this position as well as at Trp5 and Met6 in Jingzhaotoxin-V, another family 3 inhibitory cysteine knot peptide, resulted in loss in potency, indicating that hydrophobic residues at positions 5, 6 and 7 in Jingzhaotoxin-V are essential to Jingzhaotoxin-V Nav1.7 inhibitory potency (Int. Pat. Publ. No. 2014/165277). Trp5/Met6/Trp7 is also conserved in Protoxin-II, and therefore it was unexpected that polar substitutions at Trp7 can be made without loss of Protoxin-II activity with significantly improved refolding properties. Substitutions at Trp30 were shown to simultaneously improve Nav1.7 selectivity and refolding properties of the variant peptide and were unexpected since individual advantageous substitutions typically only improve a single parameter.

Table 13 shows the amino acid sequences of the select generated Protoxin-II variants.

TABLE 14 Protein Protein SEQ Name Substitution ID NO: Amino acid sequence NV1G2232 W30L 408 GPYCQKWMWTCDSERKCCEGMVCR LWCKKKLL-COOH NV1G2182 W30F 409 GPYCQKWMWTCDSERKCCEGMVCR LWCKKKLF-COOH NV1G2319 W30Y 410 GPYCQKWMWTCDSERKCCEGMVCR LWCKKKLY-COOH NV1G2329 W30G 411 GPYCQKWMWTCDSERKCCEGMVCR LWCKKKLG-COOH NV1G2129 W30I 412 GPYCQKWMWTCDSERKCCEGMVCR LWCKKKLI-COOH NV1G2291 W30V 413 GPYCQKWMWTCDSERKCCEGMVCR LWCKKKLV-COOH NV1G2156 W7Y 414 GPYCQKWMYTCDSERKCCEGMVCRL WCKKKLW-COOH NV1G2082 W7E 415 GPYCQKWMETCDSERKCCEGMVCRL WCKKKLW-COOH 63930841 W7Q 416 GPYCQKWMQTCDSERKCCEGMVCRL WCKKKLW-COOH 64087946 (−GP) 417 YCQKWMQTCDAERKCCEGFSC-(N- W7Q, S11A, M19F,  Me-Arg)-LWCKKKLL-COOH V20S, R22Me, W30L 64053366 (−GP) W7Q S11D 418 YCQKWMQTCDDERKCCEGMVCRLW W30L CKKKLL-COOH 64053340 (−GP) W7Q K14F 419 YCQKWMQTCDSERFCCEGMVCRLW W30L CKKKLL-COOH 64053236 W7Q K14F W30L 420 GPYCQKWMQTCDSERFCCEGMVCRL WCKKKLL-COOH 64053223 W7Q S11I W30L 421 GPYCQKWMQTCDIERKCCEGMVCRL WCKKKLL-COOH 63955918 W7Q W30L 422 GPYCQKWMQTCDSERKCCEGMVCRL WCKKKLL-COOH 64053210 W7Q E17N W30L 423 GPYCQKWMQTCDSERKCCNGMVCRL WCKKKLL-COOH 64087907 (−GP) W7Q 424 YCQKWMQTCDSERKCCEGMVCRLW CKKKLW-COOH 64032488 (−GP) W7Q W30L 425 YCQKWMQTCDSERKCCEGMVCRLW CKKKLL-COOH 64053301 W7Q S11V W30L 426 GPYCQKWMQTCDVERKCCEGMVCRL WCKKKLL-COOH 64053275 W7Q E17L W30L 427 GPYCQKWMQTCDSERKCCLGMVCRL WCKKKLL-COOH 64053327 (−GP) W7Q E17N 428 YCQKWMQTCDSERKCCNGMVCRLW W30L CKKKLL-COOH NV1G2324 E17Y 429 GPYCQKWMWTCDSERKCCYGMVCR LWCKKKLW-COOH NV1G2094 E17I 430 GPYCQKWMWTCDSERKCCIGMVCRL WCKKKLW-COOH NV1G1996 E17L 431 GPYCQKWMWTCDSERKCCLGMVCRL WCKKKLW-COOH

Select variants were characterized for their inhibition of Nav1.7 using veratridine-induced depolarization inhibition or Qpatch as described in Example 3. Table 15 shows the IC₅₀ values obtained. For some variants, only % inhibition (% blk; percent block of control) at a single concentration (10 nM or 30 nM) was recorded for Qpatch.

TABLE 15 hNav1.7 VERATRIDINE- Protein INDUCED Protein SEQ ID DEPOLARIZATION QP Name NO: IC50 (nM) se* IC50 (nM) % blk** se* NV1G2232 408 16.7 1.32 5.0 56.5% @ 10 nM 5.7 NV1G2182 409 17.3 1.37 3.8 54.2% @ 10 nM 5.4 NV1G2319 410 20.7 2.3 9.7 43.2% @ 10 nM 6.2 NV1G2329 411 38 2.43E+00 NV1G2129 412 47.3 3.81 −6.5% @ 10 nM 6.5 NV1G2291 413 63.3 14.9 NV1G2156 414 90.5 6.88 NV1G2082 415 90.8 11.4 63930841 416 20.9 64087946 417 23.8 20.7% @ 10 nM 10.9 64053366 418 22.1% @ 10 nM 3.5 64053340 419 26.8% @ 10 nM 3.7 64053236 420 28.0% @ 10 nM 13.2 64053223 421 33.0% @ 10 nM 5.8 63955918 422 10.8 38.50% @ 10 nM  4.5 64053210 423 41.7% @ 10 nM 6.2 64087907 424 7.1 45.1% @ 10 nM 6.0 64032488 425 6.5 45.6% @ 10 nM 4.6 64053301 426 10.7 45.83% @ 10 nM  3.3 64053275 427 2.9 48.22% @ 10 nM  5.2 64053327 428 7.9 51.9% @ 10 nM 2.6 NV1G2324 429 57.5% @ 10 nM 3.9 NV1G2094 430 63.2% @ 30 nM 6.2 NV1G1996 431 0.5 76.9% @ 10 nM 2.3 *se; standard error **% blk: % block QP: QPatch

Select variants were tested against various human Nav1.x channels. Table 16 shows the results of those experiments. IC₅₀ values for each channel were measured using QPatch.

TABLE 16 Protein Protein SEQ ID IC₅₀ (nM) Name Substitution NO: Nav1.1 Nav1.2 Nav1.4 Nav1.6 NV1G2232 W30L 408 3847.0 562.7 NV1G2182 W30F 409 239.6 732.2 253.1 NV1G2319 W30Y 410 1704.0 63930841 W7Q 416 543.1 64087946 (-GP) 417 2586.0 W7Q, S11A, M19F, V20S, R22Me, W30L 63955918 W7Q W30L 422 1951.0 17000.0 1987.0 64087907 (-GP) W7Q 424 1460.0 64032488 (-GP) W7Q 425 1336.0 1842.0 W30L 64053301 W7Q S11V 426 15340.0 19350.0 2244.0 W30L 64053275 W7Q E17L 427 3868.0 136.7 2219.0 W30L 64053327 (-GP) W7Q 428 6391.0 6656.0 3867.0 E17N W30L

Protoxin-II variants were expressed and purified as described in Example 1, or synthesized by standard solid phase synthesis methods. The yields of the recombinant or synthetic peptides were compared to the yields of the wild-type Protoxin-II. Table 17 shows that the yields of the select Protoxin-II variants were significantly higher than that of Protoxin-II, indicating improved folding properties of the variants. The scale of the solid-phase synthesis was 0.1 mmol.

TABLE 17 total yield Protein name Substitution (mg) NV1D12 (Protoxin-II with 3.8 N-terminal GP) 63930841 W7Q 14.4 NV1G2232 W30L 14.5 63955918 W7Q, W30L 16.2 NV1G1996 E17L 1.8 64053275 E17L W7Q W30L 13.0

Example 7. Protoxin-II Variants are Efficacious in In Vivo Models of Pain Following Intrathecal Administration

Efficacy of select Protoxin-II variants in reducing pain after intrathecal administration was evaluated.

Peptides NV1D2775-OH, NV1D3034 and 63955918 were used in the studies. Animal models that measure acute thermal pain (tail flick and hot plate) and injury-induced pain (formalin flinching) were used.

Tail-Flick Test:

The animals were placed on a tail-flick device (Ugo Basile). The device has a focal infrared light heating area (diameter-5 mm). The tail (⅓-½ way from distal end) of the animal was placed on the focal heating area. The temperature of the heat source was adjusted to elicit a tail-flick within 10 seconds in animals treated with vehicle. A 15 second cut-off time was used to prevent tissue damage, as is standard in the literature. The time elapsed between the start of the heat stimulus and any avoidance response was measured automatically and recorded for the test groups.

Hot Plate Test:

Animals were placed on a 10″×10″ metal plate surrounded by 4 Plexiglas walls (15 inches high). The plate was maintained at a temperature of 52.5° C. The response latency (time when the animal first flinches or licks its hind paw, jumps, or vocalizes) was measured and the animal removed from the plate. Animals showing no response were removed from the plate after 30 s to prevent any possible tissue damage.

Formalin Flinching:

Formalin-induced pain behavior (i.e. paw flinches) was measured using an automated “flinch response” measuring device manufactured by UCSD. The device detects any sudden movement of a metal band glued onto one hind paw of the animal using a motion sensor installed underneath the device floor. One-half to one hour prior to formalin injection, a small metal band was attached to the plantar surface of one hind paw using a small drop of cyanoacrylate and the animal was placed in the testing chamber to be acclimatized. Formalin (2.5%, 50 μL) was injected subcutaneously into the dorsum of the paw with the metal band. The animal was placed in the customized cylinder (25×10×20 cm, San Diego Instrument) immediately after intraplantar formalin injection. Paw flinches were recorded automatically.

In the acute thermal pain models, Protoxin-II variant 63955918 produced potent and prolonged analgesia as indicated by the elevated latency in the tail flick test (FIG. 11A and FIG. 11B) and hot plate test (FIG. 11C, FIG. 11D) after a single intrathecal administration. The significance and duration of the analgesia was dose-dependent.

Hindpaw formalin injection is a commonly used model for injury-induced pain. The injection induces a characteristic, bi-phasic flinching behavior, which indicates pain in test animals. As shown in FIG. 11E, animals pretreated with intrathecal injection of Protoxin-II variant 63955918 demonstrated less flinches in the formalin test, suggesting an inhibition of injury-induced pain.

Similarly, peptides NV1D2775-OH and NV1D3034 demonstrated significant efficacy in the tail flick, hot plate and formalin test (FIG. 12A, FIG. 12B, FIG. 12C, FIG. 12D, FIG. 12E, FIG. 13A, FIG. 13B, FIG. 13C, FIG. 13D, FIG. 13E) following a single intrathecal administration.

Example 8. Characterization of Additional Protoxin-II Variants

Additional Protoxin-II variants were designed and expressed using the strategies and methods described in Example 6, and characterized in veratridine-induced depolarization inhibition and/or Qpatch according to the protocols described in Example 3.

Table 18 shows the amino acid sequence of the select generated Protoxin-II variants.

TABLE 18 ID Mutation SEQ ID NO: Sequence NV1G2228 E12R 434 GPYCQKWMWTCDSRRKCCEGMVCRLWCKKK LW-COOH NV1G2072 E12T 435 GPYCQKWMWTCDSTRKCCEGMVCRLWCKKK LW-COOH NV1G2008 S11N 436 GPYCQKWMWTCDNERKCCEGMVCRLWCKK KLW-COOH NV1G1994 T8F 437 GPYCQKWMWFCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2070 S11T 438 GPYCQKWMWTCDTERKCCEGMVCRLWCKKK LW-COOH NV1G2074 Y1N 439 GPNCQKWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2079 E17A 440 GPYCQKWMWTCDSERKCCAGMVCRLWCKK KLW-COOH NV1G2073 E17D 441 GPYCQKWMWTCDSERKCCDGMVCRLWCKK KLW-COOH NV1G2076 Y1I 442 GPICQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G1864 Y1S, W7Q, 443 GPSCQKWMQTCDIRRKCCEGFSCRLWCKKKL S11I S11I, E12R, W-COOH M19F, V20S NV1G2039 S11I 444 GPYCQKWMWTCDIERKCCEGMVCRLWCKKK LW-COOH NV1G1007 Y1Q, W7Q, 445 GPQCQKWMQTCDAERKCCEGFVCRLWCKKK W30trypto- S11A, M19F, L-(tryptophanol) phanol C- terminal alcohol NV1G2238 K14P 446 GPYCQKWMWTCDSERPCCEGMVCRLWCKKK LW-COOH NV1G2198 Y1K 447 GPKCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2195 E12V 448 GPYCQKWMWTCDSVRKCCEGMVCRLWCKK KLW-COOH NV1G1153-N- Y1Q, W7Q, 449 GPQCQKWMQTCDRERKCCEGFVCTLWCRKKL methyl S11R, M19F, W-(methylamide) R22T, K26R, C- terminal methylamide NV1G2007 S11L 450 GPYCQKWMWTCDLERKCCEGMVCRLWCKKK LW-COOH NV1G2140 E17P 451 GPYCQKWMWTCDSERKCCPGMVCRLWCKKK LW-COOH NV1G2003 T8Y 452 GPYCQKWMWYCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2236 Y1L 453 GPLCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2164 YlV 454 GPVCQKWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G1864 Y1S, W7Q, 455 GPSCQKWMQTCDARRKCCLGFSCRLWCKKKL E17L S11A, E12R, W-COOH E17L, V20S (−GP) (−GP) 109 SCQKWMQTCDAERKCCEGFVCRLWCKKKLW- NV1G1001 Y1S, W7Q, COOH S11A, M19F NV1G2149 T8L 456 GPYCQKWMWLCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2226 V20I 457 GPYCQKWMWTCDSERKCCEGMICRLWCKKK LW-COOH NV1G2286 T8K 458 GPYCQKWMWKCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2128 E12H 459 GPYCQKWMWTCDSHRKCCEGMVCRLWCKK KLW-COOH NV1G2041 K4E, E17R 460 GPYCQEWMWTCDSERKCCRGMVCRLWCKKK LW-COOH NV1G2001 T8G 461 GPYCQKWMWGCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2019 K4E, W5F, 462 GPYCQEFLWTCDSTRKCCEGMVCRLWCKKKL M6L, E12T W-COOH NV1G2002 K14H 463 GPYCQKWMWTCDSERHCCEGMVCRLWCKK KLW-COOH NV1G2225 E17R 464 GPYCQKWMWTCDSERKCCRGMVCRLWCKKK LW-COOH NV1G2012 K14V 465 GPYCQKWMWTCDSERVCCEGMVCRLWCKKK LW-COOH NV1G2020 Y1S, M6F, 466 GPSCQKWFWTCDRTRKCCEGLVCRLWCKKKL A11R, E12T, W-COOH M19L NV1G2334 E17K 467 GPYCQKWMWTCDSERKCCKGMVCRLWCKKK LW-COOH NV1G2025 Y1Q, W7Q, 468 GPQCQKWMQTCDATRKCCEGFVCRLWCKKK S11A, E12T, LW-COOH M19F NV1G2131 E12Y 469 GPYCQKWMWTCDSYRKCCEGMVCRLWCKKK LW-COOH NV1G1007 Y1Q, W7Q, 470 GPQCQKWMQTCDITRKCCEGFVCRLWCKKKL A11I, E12T S11I, E12T, W-COOH M19F NV1G2268 Y1F 471 GPFCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2332 E17S 472 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2010 T8V 473 GPYCQKWMWVCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2053 Y1T 474 GPTCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G1519 Y1Q, W7Q, 133 GPQCQKWMQTCDARRKCCEGFVCRLWCKKK S11A, E12R, LW-COOH M19F NV1G2253 E12I 475 GPYCQKWMWTCDSIRKCCEGMVCRLWCKKK LW-COOH NV1G2055 E12L 476 GPYCQKWMWTCDSLRKCCEGMVCRLWCKKK LW-COOH NV1G2338 K4R 477 GPYCQRWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2030 K14F 478 GPYCQKWMWTCDSERFCCEGMVCRLWCKKK LW-COOH NV1G2024 Y1S, M6F, 479 GPSCQKWFWTCDANRKCCEGLVCRLWCKKKL S11A, E12N, W-COOH M19L NV1G2004 K14Y 480 GPYCQKWMWTCDSERYCCEGMVCRLWCKKK LW-COOH NV1G2336 M6L 481 GPYCQKWLWTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2011 E17F 482 GPYCQKWMWTCDSERKCCFGMVCRLWCKKK LW-COOH NV1G2080 W5Y 483 GPYCQKYMWTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2288 D10R 484 GPYCQKWMWTCRSERKCCEGMVCRLWCKKK LW-COOH NV1G2142 K14R 485 GPYCQKWMWTCDSERRCCEGMVCRLWCKKK LW-COOH NV1G2232 W30L 408 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LL-COOH NV1G2193 E12D 486 GPYCQKWMWTCDSDRKCCEGMVCRLWCKK KLW-COOH NV1G2230 S11D 487 GPYCQKWMWTCDDERKCCEGMVCRLWCKK KLW-COOH NV1G2182 W30F 409 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LF-COOH NV1G1153C- Y1Q, W7Q, 488 GPQCQKWMQTCDRERKCCEGFVCTLWCRKKL terminal S11R, M19F, W-(palmitoyl-lysine)-COOH palmitoyl- R22T, K26R, lysine addition of palmitoyl- lysine at position 33 NV1G2339 T8A 489 GPYCQKWMWACDSERKCCEGMVCRLWCKK KLW-COOH NV1G2016 Y1S, M6F, 490 GPSCQKWFWTCDRERKCCEGLVCRLWCKKKL S11R, M19L W-COOH NV1G2017 Y1Q, K4E, 491 GPQCQEFLWTCDSERKCCEGMVCRLWCKKKL W5F, M6L W-COOH NV1G2111 E17N 492 GPYCQKWMWTCDSERKCCNGMVCRLWCKK KLW-COOH NV1G2330 R22S 493 GPYCQKWMWTCDSERKCCEGMVCSLWCKKK LW-COOH NV1G2204 E17T 494 GPYCQKWMWTCDSERKCCTGMVCRLWCKKK LW-COOH NV1G2026 Y1S, M6F, 495 GPSCQKWFWTCDATRKCCEGLVCRLWCKKKL S11A, E12T, W-COOH M19L NV1G1007 Y1Q, W7Q, 496 GPQCQKWMQTCDAERKCCEGFVCRLWCKKK with C- S11A, M19F, LWGGGGG-COOH terminal 5x addition Gly of 5xGly at positions 31-35 NV1G2038 L23F 497 GPYCQKWMWTCDSERKCCEGMVCRFWCKKK LW-COOH NV1G2305 R22H 498 GPYCQKWMWTCDSERKCCEGMVCHLWCKK KLW-COOH NV1G2021 K4E, W5F, 499 GPYCQEFLWTCDRTRKCCEGMVCRLWCKKKL M6L, S11R, W-COOH E12T NV1G2319 W30Y 410 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LY-COOH NV1G2100 E12G 500 GPYCQKWMWTCDSGRKCCEGMVCRLWCKK KLW-COOH NV1G2130 Y1D 501 GPDCQKWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2081 K4D 502 GPYCQDWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2252 T8H 503 GPYCQKWMWHCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2040 K26Y 504 GPYCQKWMWTCDSERKCCEGMVCRLWCYKK LW-COOH NV1G2146 G18P 505 GPYCQKWMWTCDSERKCCEPMVCRLWCKKK LW-COOH NV1G1153-N- Y1Q, W7Q, 506 GPQCQKWMQTCDRERKCCEGFVCTLWCRKKL ethyl S11R, M19F, W-(ethylamide) R22T, K26R, C- terminal ethylamide NV1G2098 E17H 507 GPYCQKWMWTCDSERKCCHGMVCRLWCKK KLW-COOH NV1G2191 L29H 508 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK HW-COOH NV1G2333 G18K 509 GPYCQKWMWTCDSERKCCEKMVCRLWCKKK LW-COOH NV1G2224 K14S 510 GPYCQKWMWTCDSERSCCEGMVCRLWCKKK LW-COOH NV1G1001-N- (−GP) 511 SCQKWMQTCDAERKCCEGFVCRLWCKKKLW- ethyl Y1S, W7Q, (ethylamide) S11A, M19F, C-terminal ethylamide NV1G1996 E17L 431 GPYCQKWMWTCDSERKCCLGMVCRLWCKKK LW-COOH NV1G2337 K14Q 512 GPYCQKWMWTCDSERQCCEGMVCRLWCKK KLW-COOH NV1G2301 V20T 513 GPYCQKWMWTCDSERKCCEGMTCRLWCKKK LW-COOH NV1G2075 K4T 514 GPYCQTWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2278 R22N 515 GPYCQKWMWTCDSERKCCEGMVCNLWCKK KLW-COOH NV1G2014 W24H 516 GPYCQKWMWTCDSERKCCEGMVCRLHCKKK LW-COOH NV1G2065 Y1Q, W7Q, 517 GPQCQKWMQTCDRTRKCCEGFVCRLWCKKKL S11R, E12T, W-COOH M19F NV1G2099 L29V 518 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK VW-COOH NV1G1007 Y1Q, W7Q, 519 GPQCQKWMQTCDAERKCCLGFVCRLWCKKKL E17L S11A, E17L, W-COOH M19F NV1G1007 Y1Q, W7Q, 520 GPQCQKWMQTCDAERKCCEGFVCRLWCKKK G33 S11A, M19F, LWG-COOH addition of Gly at position 33 1007 A11I Y1Q, W7Q, 521 GPQCQKWMQTCDIERKCCEGFVCRLWCKKKL S11I, M19F W-COOH NV1G2221 K27A 522 GPYCQKWMWTCDSERKCCEGMVCRLWCKAK LW-COOH NV1G2097 K14I 523 GPYCQKWMWTCDSERICCEGMVCRLWCKKK LW-COOH NV1G2029 W5L 524 GPYCQKLMWTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2257 S11V 525 GPYCQKWMWTCDVERKCCEGMVCRLWCKK KLW-COOH NV1G1998 V20H 526 GPYCQKWMWTCDSERKCCEGMHCRLWCKKK LW-COOH NV1G2068 R13Y 527 GPYCQKWMWTCDSEYKCCEGMVCRLWCKKK LW-COOH NV1G1001 Y1S, W7Q, 65 GPSCQKWMQTCDAERKCCEGFVCRLWCKKKL S11A, M19F W-COOH NV1G2137 V20K 528 GPYCQKWMWTCDSERKCCEGMKCRLWCKKK LW-COOH NV1G2199 S11H 529 GPYCQKWMWTCDHERKCCEGMVCRLWCKK KLW-COOH NV1G2300 K27G 530 GPYCQKWMWTCDSERKCCEGMVCRLWCKG KLW-COOH NV1G2124 R13H 531 GPYCQKWMWTCDSEHKCCEGMVCRLWCKK KLW-COOH NV1G2254 T8P 532 GPYCQKWMWPCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2239 K4N 533 GPYCQNWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2255 K4E, E17K 534 GPYCQEWMWTCDSERKCCKGMVCRLWCKKK LW-COOH NV1G2256 K14G 535 GPYCQKWMWTCDSERGCCEGMVCRLWCKK KLW-COOH NV1G2095 K14T 536 GPYCQKWMWTCDSERTCCEGMVCRLWCKKK LW-COOH NV1G2220 L29S 537 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK SW-COOH NV1G2154 T8Q 538 GPYCQKWMWQCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2329 W30G 411 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LG-COOH NV1G2122 R13K 539 GPYCQKWMWTCDSEKKCCEGMVCRLWCKKK LW-COOH NV1G1007 C- Y1Q, W7Q, 540 GPQCQKWMQTCDAERKCCEGFVCRLWCKKK terminal S11A, M19F, LW-(palmitoyl-lysine)-COOH palmitoyl- addition lysine of palmitoyl- lysine at position 33 NV1G2000 R22Y 541 GPYCQKWMWTCDSERKCCEGMVCYLWCKKK LW-COOH NV1G2009 G18Y 542 GPYCQKWMWTCDSERKCCEYMVCRLWCKKK LW-COOH NV1G2066 K4E, W5F, 543 GPYCQEFLWTCDSERKCCEGMVCRLWCRKKL M6L, K26R W-COOH NV1G2083 W7S 544 GPYCQKWMSTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2126 K4G 545 GPYCQGWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G2043 (−GP) 370 GPCRTIGPSVCQCQKWMQTCDRERKCCEGFV Y1Q, W7Q, CTLWCRKKLW-COOH S11R, M19F, R22T, K26R + N-term GPCRTIGPS VC NV1G2050 W7R 546 GPYCQKWMRTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2071 K26T 547 GPYCQKWMWTCDSERKCCEGMVCRLWCTKK LW-COOH NV1G2129 W30I 412 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LI-COOH NV1G2086 R22V 548 GPYCQKWMWTCDSERKCCEGMVCVLWCKKK LW-COOH NV1G2057 Y1Q, W7Q, 341 GPQCQKWMQTCDRERKCCEGFVCTLWCRKKL S11R, M19F, WGSAPAPAPAPAPGSCCNCSSKWCRDHSRCC R22T, K26R + -COOH C-term GSAPAPAP APAPGSCC NCSSKWCR DHSRCC NV1G2093 V20E 549 GPYCQKWMWTCDSERKCCEGMECRLWCKKK LW-COOH NV1G1995 D10F 550 GPYCQKWMWTCFSERKCCEGMVCRLWCKKK LW-COOH NV1G2312 K27H 551 GPYCQKWMWTCDSERKCCEGMVCRLWCKH KLW-COOH NV1G2176 K4S 552 GPYCQSWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2046 K28N 553 GPYCQKWMWTCDSERKCCEGMVCRLWCKK NLW-COOH NV1G2047 W5E 554 GPYCQKEMWTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2170 V20R 555 GPYCQKWMWTCDSERKCCEGMRCRLWCKKK LW-COOH NV1G2042 T8E 556 GPYCQKWMWECDSERKCCEGMVCRLWCKKK LW-COOH NV1G2117 K14E 557 GPYCQKWMWTCDSERECCEGMVCRLWCKKK LW-COOH NV1G1999 R22G 558 GPYCQKWMWTCDSERKCCEGMVCGLWCKK KLW-COOH NV1G2247 K28V 559 GPYCQKWMWTCDSERKCCEGMVCRLWCKKV LW-COOH NV1G2054 D10R, E12R 560 GPYCQKWMWTCRSRRKCCEGMVCRLWCKKK LW-COOH NV1G1007 Y1Q, W7Q, 561 GPQCQKWMQTCDAERKCCFGFVCRLWCKKK E17F S11A, E17F, LW-COOH M19F NV1G2056 D10V 562 GPYCQKWMWTCVSERKCCEGMVCRLWCKKK LW-COOH NV1G1007 Y1Q, W7Q, 563 GPQCQKWMQTCDAERKCCEGFVCTLWCRKKL D33 S11A, M19 WD-COOH F, addition of Dat position 33 NV1G2291 W30V 413 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LV-COOH NV1G2306 K26S 564 GPYCQKWMWTCDSERKCCEGMVCRLWCSKK LW-COOH NV1G2023 Y1S, M6F, 565 GPSCQKWFWTCDAERKCCEGLVCRLWCRKKL S11A, M19L, W-COOH K26R NV1G2133 K28H 566 GPYCQKWMWTCDSERKCCEGMVCRLWCKK HLW-COOH NV1G2070 S11T 567 GPYCQKWMWTCDTERKCCEGMVCRLWCKKK LW-COOH NV1G2317 K28D 568 GPYCQKWMWTCDSERKCCEGMVCRLWCKK DLW-COOH NV1G2116 K27T 569 GPYCQKWMWTCDSERKCCEGMVCRLWCKTK LW-COOH NV1G2174 R22Q 570 GPYCQKWMWTCDSERKCCEGMVCQLWCKK KLW-COOH NV1G2209 K14N 571 GPYCQKWMWTCDSERNCCEGMVCRLWCKK KLW-COOH NV1G2134 W7H 572 GPYCQKWMHTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2166 K4P 573 GPYCQPWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2119 Q3G 574 GPYCGKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2285 D10Q 575 GPYCQKWMWTCQSERKCCEGMVCRLWCKKK LW-COOH NV1G2067 Y1S, K4E, 576 GPSCQEFLWTCDAERKCCEGLVCRLWCKKKLW- W5F, M6L, COOH S11A, M19L NV1G2299 K27L 577 GPYCQKWMWTCDSERKCCEGMVCRLWCKLK LW-COOH NV1G2316 V20Y 578 GPYCQKWMWTCDSERKCCEGMYCRLWCKKK LW-COOH NV1G2322 L29N 579 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK NW-COOH NV1G2156 W7Y 414 GPYCQKWMYTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2082 W7E 415 GPYCQKWMETCDSERKCCEGMVCRLWCKKKL W-COOH NV1G2165 D10A 580 GPYCQKWMWTCASERKCCEGMVCRLWCKKK LW-COOH NV1G2201 V20L 581 GPYCQKWMWTCDSERKCCEGMLCRLWCKKK LW-COOH NV1G2077 Q3F 582 GPYCFKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2173 V20A 583 GPYCQKWMWTCDSERKCCEGMACRLWCKKK LW-COOH NV1G2207 S11Y 584 GPYCQKWMWTCDYERKCCEGMVCRLWCKKK LW-COOH 64087946 (−GP) 417 YCQKWMQTCDAERKCCEGFSC-(N-Me-Arg)- W7Q, S11A, LWCKKKLL-COOH M19F, V20S, R22Me, W30L 64053366 (−GP) W7Q 418 YCQKWMQTCDDERKCCEGMVCRLWCKKKLL- S11D W30L COOH 64087868 W7Q L29V 585 GPYCQKWMQTCDSERKCCEGMVCRLWCKKK VW-COOH NV1G2266 R13L 586 GPYCQKWMWTCDSELKCCEGMVCRLWCKKK LW-COOH NV1G2287 D10R, E12R, 587 GPYCQKWMWTCRSREKCCEGMVCRLWCKKK R13E LW-COOH NV1G2041 K4E/E17R 588 GPYCQEWMWTCDSERKCCRGMVCRLWCKKK LW-COOH 64053340 (−GP) W7Q 419 YCQKWMQTCDSERFCCEGMVCRLWCKKKLL- K14F W30L COOH 64053236 W7Q K14F 420 GPYCQKWMQTCDSERFCCEGMVCRLWCKKK W30L LL-COOH 64087881 D10, E12, 589 GPQCQKWMQTC-(L-aspartyl-4- E17 side aminobutane)-A-(glutamyl-4 chains and aminobutane)-RKCC-(glutamyl-4- C-terminus aminobutane)-GFVCRLWCKKKLW- derviatized (putrescine) with putrescine NV1G2217 T8I 590 GPYCQKWMWICDSERKCCEGMVCRLWCKKK LW-COOH NV1G2183 K4D, E17R 591 GPYCQDWMWTCDSERKCCRGMVCRLWCKK KLW-COOH 64087894 (−GP) 592 YCQKWMQTCDIERKCCEGFVCRLWCKKKLW- W7Q, S11I, COOH M19F 64053223 W7Q S11I 421 GPYCQKWMQTCDIERKCCEGMVCRLWCKKKL W30L L-COOH NV1G2216 K28T 593 GPYCQKWMWTCDSERKCCEGMVCRLWCKKT LW-COOH NV1G2210 D10G 594 GPYCQKWMWTCGSERKCCEGMVCRLWCKKK LW-COOH NV1G2314 G18H 595 GPYCQKWMWTCDSERKCCEHMVCRLWCKKK LW-COOH 64032501 (−GP) W7Q 596 YCQKWMQTCDIERKCCEGMVCRLWCKKKLW- S11I COOH 63955918 W7Q W30L 422 GPYCQKWMQTCDSERKCCEGMVCRLWCKKK LL-COOH NV1G2088 S11F 597 GPYCQKWMWTCDFERKCCEGMVCRLWCKKK LW-COOH NV1G2289 K27F 598 GPYCQKWMWTCDSERKCCEGMVCRLWCKFK LW-COOH 64053210 W7Q E17N 423 GPYCQKWMQTCDSERKCCNGMVCRLWCKKK W30L LL-COOH 64053210 W7Q E17N 423 GPYCQKWMQTCDSERKCCNGMVCRLWCKKK W30L LL-COOH 64087907 (−GP) W7Q 424 YCQKWMQTCDSERKCCEGMVCRLWCKKKLW- COOH 64032488 (−GP) W7Q 425 YCQKWMQTCDSERKCCEGMVCRLWCKKKLL- W30L COOH 63955931 Y1Q, W7Q, 599 GPQCQKWMQTCDAERKCCEGFVC-(N- S11A, M19F, omega-methyl-L-arginine)-LWCKKKLW- R22N- COOH omega- methyl-L- arginine 64053301 W7Q S11V 426 GPYCQKWMQTCDVERKCCEGMVCRLWCKKK W30L LL-COOH NV1G2243 L29F 600 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK FW-COOH NV1G2227 Q3S 601 GPYCSKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH 64053275 W7Q E17L 427 GPYCQKWMQTCDSERKCCLGMVCRLWCKKK W30L LL-COOH 64053275 W7Q E17L 427 GPYCQKWMQTCDSERKCCLGMVCRLWCKKK W30L LL-COOH 64087920 Y1Q, W7Q, 602 GPQCQKWMQTCDAERKCCEG-(4-chloro- S11A, M19 Phe)-VCRLWCKKKLW-COOH (4-CI-Phe) 64053327 (−GP) W7Q 428 YCQKWMQTCDSERKCCNGMVCRLWCKKKLL- E17N COOH W30L NV1G2233 E12Q 603 GPYCQKWMWTCDSQRKCCEGMVCRLWCKK KLW-COOH NV1G2265 Q3Y 604 GPYCYKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G2172 K27V 605 GPYCQKWMWTCDSERKCCEGMVCRLWCKVK LW-COOH NV1G2248 E17V 606 GPYCQKWMWTCDSERKCCVGMVCRLWCKK KLW-COOH NV1G2039 S11I 607 GPYCQKWMWTCDIERKCCEGMVCRLWCKKK LW-COOH NV1G2229 G18R 608 GPYCQKWMWTCDSERKCCERMVCRLWCKKK LW-COOH NV1G2099 L29V 609 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK VW-COOH NV1G2324 E17Y 429 GPYCQKWMWTCDSERKCCYGMVCRLWCKKK LW-COOH NV1G2096 K27I 610 GPYCQKWMWTCDSERKCCEGMVCRLWCKIK LW-COOH NV1G2094 E17I 430 GPYCQKWMWTCDSERKCCIGMVCRLWCKKK LW-COOH NV1G1996 E17L 431 GPYCQKWMWTCDSERKCCLGMVCRLWCKKK LW-COOH NV1G2039 (−GP) S11I 611 YCQKWMWTCDIERKCCEGMVCRLWCKKKLW- (−GP) COOH 63930854 Y1Q, W7Q, 612 GPQCQKWMQTCDIERKCCLGFVCRLWCKKKL S11I, E17L, W-COOH M19F 63909404 Y1Q, W7Q, 613 GPQCQKWMQTCDIERKCCEGFVCRLWCKKKV S11I, M19F, W-COOH L29V 63930880 Y1Q, W7Q, 614 GPQCQKWMQTCDAERKCCLGFVCRLWCKKK S11A, E17L, VW-COOH M19F, L29V 63909378 Y1Q, W7Q, 615 GPQCQKWMQTCDAERKCCEGFVCRLWCKKK S11A, M19F, VW-COOH L29V 63930841 W7Q 416 GPYCQKWMQTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G714 Y1Q 616 GPQCQKWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G690 Y15 617 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G688 Y1R 618 GPRCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G700 S11A 619 GPYCQKWMWTCDAERKCCEG MVCRLWCKK KLW-COOH NV1G692 Y1A 620 GPACQKWMWTCDSERKCCEGMVCRLWCKK KLW-COOH NV1G1051 T85 621 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LW-COOH NV1G702 S11R 622 GPYCQKWMWTCDRERKCCEGMVCRLWCKK KLW-COOH NV1D1328_1 M6F 623 GPYCQKWFWTCDSERKCCEGMVCRLWCKKKL W-COOH NV1G694 W7Q 624 GPYCQKWMQTCDSERKCCEGMVCRLWCKKK LW-COOH NV1D1339_1 L23T 625 GPYCQKWMWTCDSERKCCEGMVCRTWCKKK LW-COOH NV1G698 D10S 626 GPYCQKWMWTCSSERKCCEGMVCRLWCKKK LW-COOH NV1G1055 W30S 627 GPYCQKWMWTCDSERKCCEGMVCRLWCKKK LS-COOH NV1G1635 K14A 628 GPYCQKWMWTCDSERACCEGMVCRLWCKKK LW-COOH NV1G224 M19S 629 GPYCQKWMWTCDSERKCCEGFVCRLWCKKKL W-COOH NV1G704 V20S 630 GPYCQKWMWTCDSERKCCEGMSCRLWCKKK LW-COOH NV1D1335_1 K14D 631 GPYCQKWMWTCDSERDCCEGMVCRLWCKK KLW-COOH NV1G1057 K27R 632 GPYCQKWMWTCDSERKCCEGMVCRLWCKRK LW-COOH NV1G217 E12S 633 GPYCQKWMWTCDSSRKCCEG MVCRLWCKKK LW-COOH NV1G225 R22K 634 GPYCQKWMWTCDSERKCCEGMVCKLWCKKK LW-COOH NV1G696 T8R 635 GPYCQKWMWRCDSERKCCEGMVCRLWCKKK LW-COOH NV1D1331_1 S11P 636 GPYCQKWMWTCDPERKCCEGMVCRLWCKKK LW-COOH NV1G1047 K28R 637 GPYCQKWMWTCDSERKCCEGMVCRLWCKKR LW-COOH NV1G576 M19Y 638 GPYCQKWMWTCDSERKCCEGYVCRLWCKKKL W-COOH NV1G581 M19F 639 GPYCQKWMWTCDSERKCCEGFVCRLWCKKKL W-COOH NV1D1338 1_ L23R 640 GPYCQKWMWTCDSERKCCEGMVCRRWCKK KLW-COOH NV1D1333_1 R13N 641 GPYCQKWMWTCDSENKCCEGMVCRLWCKK Protoxin-II KLW-COOH NV1G2349 L23K (+GP) 642 GPYCQKWMWTCDSERKCCEGMVCRKWCKK Protoxin-II KLW-COOH NV1G585 M19R 643 GPYCQKWMWTCDSERKCCEGRVCRLWCKKK (+GP) LW-COOH Protoxin-II W7Q 64151490 W30L 644 GPYCQKWMQTCDSERKCCEGMVC-(N- R22Me(2) omega, N-omega-dimethyl(asymmetric)-L- (+GP) arginine)-LWCKKKLL-COOH NV1G587 Protoxin-II 645 GPYCQKWMWTCDSERKCCEGNVCRLWCKKK M19N LW-COOH (+GP) NV1G2352 Protoxin-II 646 GPYCQQWMWTCDSERKCCEGMVCRLWCKK K4Q (+GP) KLW-COOH NV1G2035 Protoxin-II 647 GPYCQKWMWTCDSERKCCENMVCRLWCKKK G18N LW-COOH (+GP) NV1G2351 Protoxin-II 648 GPYCQKWMWTCDSERKCCGGMVCRLWCKK E17G (+GP) KLW-COOH NV1G2346 Protoxin-II 649 GPYCQKWMWTCDGERKCCEGMVCRLWCKK S11G (+GP) KLW-COOH NV1G2341 Protoxin-II 650 GPYCQKWMWTCDSERKCCEGMFCRLWCKKK V20F (+GP) LW-COOH NV1G2342 Protoxin-II 651 GPYCQKWMWTCTSERKCCEGMVCRLWCKKK D10T (+GP) LW-COOH NV1G2348 Protoxin-II 652 GPYCQKWMWTCDSERKCCEGMVCRLWCKK K28Q (+GP) QLW-COOH NV1G1934 Protoxin-II 653 GPYCQKWMWTCDEERKCCEGMVCRLWCKKK SHE (+GP) LW-COOH NV1G2347 Protoxin-II 654 GPYCQHWMWTCDSERKCCEGMVCRLWCKK K4H (+GP) KLW-COOH NV1G584 Protoxin-II 655 GPYCQKWMWTCDSERKCCEGHVCRLWCKKK M19H LW-COOH (+GP) NV1G2033 Protoxin-II 656 GPYCQKWMWTCDSERKCCEGMVCRIWCKKK L23I (+GP) LW-COOH NV1G2343 Protoxin-II 657 GPYCRKWMWTCDSERKCCEGMVCRLWCKKK Q3R (+GP) LW-COOH NV1G2344 Protoxin-II 658 GPHCQKWMWTCDSERKCCEGMVCRLWCKK Y1H (+GP) KLW-COOH NV1G2345 Protoxin-II 659 GPGCQKWMWTCDSERKCCEGMVCRLWCKK Y1G (+GP) KLW-COOH NV1G2034 Protoxin-II 660 GPYCQKWMWTCDSERKCCEGMVCRLGCKKK W24G LW-COOH (+GP) NV1G594 Protoxin-II 661 GPYCQKWKWTCDSERKCCEGMVCRLWCKKK M6K (+GP) LW-COOH NV1G1041 Protoxin-II 662 GPYCQKWMWTCDQERKCCEGMVCRLWCKK S11Q (+GP) KLW-COOH

Select variants were characterized for their inhibition of Nav1.7 using veratridine-induced depolarization inhibition or Qpatch as described in Example 3. Table 19 shows the IC₅₀ values obtained. For some variants, only % inhibition (% blk; percent block of control) at single concentration (10 nM or 30 nM) was recorded for Qpatch. se; standard error.

TABLE 19 hNav1.7 VERATRIDINE- INDUCED DEPOLAR- SEQ IZATION QP ID IC₅₀ IC₅₀ Peptide ID NO: (nM) ± (nM) se % blk se NV1G2228 434 4.69 2.70E−01 59.8% @ 10 nM 7.2 NV1G2072 435 4.71 0.291 82.2% @ 10 nM 2.5 NV1G2008 436 5.6 0.6 57.1% @ 10 nM 4.6 NV1G1994 437 6.5 0.3 4.138 69.1% @ 10 nM 7.8 NV1G2070 438 6.46 0.438 2.8889 74.5% @ 10 nM 4.6 NV1G2074 439 6.48 0.482 71.3% @ 10 nM 3.3 NV1G2079 440 6.65 0.608 69.4% @ 10 nM 3.2 NV1G2073 441 6.73 0.572 4.6 71.2% @ 10 nM 3.9 NV1G2076 442 6.93 0.764 2.77 76.1% @ 10 nM 2.2 NV1G1864 443 22.3 0.141 52.3% @ 10 nM 7.8 S11I NV1G2039 444 7.15 0.579 2.586 71.8% @ 10 nM 0.8 NV1G1007 445 13.3 1.17 1.4 65.8% @ 10 nM 2.9 W30tryptophanol NV1G2238 446 7.47 5.84E−01 32.1% @ 10 nM 9.8 NV1G2198 447 7.49 0.856 37.6% @ 10 nM 7.6 NV1G2195 448 7.66 0.48 62.4% @ 10 nM 2.4 NV1G1153-N- 449 7.1 0.9 1.2 1.3 56.1% @ 30 nM 7.9 methyl NV1G2007 450 8.4 1.1 46.5% @ 10 nM 2.4 NV1G2140 451 8.55 1.46 NV1G2003 452 8.8 1.5 51.8% @ 10 nM 5.1 NV1G2236 453 9.12 7.75E−01 45.3% @ 10 nM 4.3 NV1G2164 454 9.37 0.507 NV1G1864 455 9.38 5.32E−01 28.4% @ 10 nM 18.2 E17L (-GP) 109 9.47 1.28 2.6 1.4 50.9% @ 10 nM 4.7 NV1G1001 NV1G2149 456 9.61 0.834 62.3% @ 10 nM 4.6 NV1G2226 457 9.71 7.19E−01 24.2% @ 10 nM 6.0 NV1G2286 458 9.85 0.923 NV1G2128 459 9.94 0.945 63.8% @ 10 nM 4.9 NV1G2041 460 9.98 1.07 4.791 53.4% @ 10 nM 4.4 NV1G2001 461 10.9 0.6 39.9% @ 10 nM 5.6 NV1G2019 462 11 0.787 44.2% @ 10 nM 4.0 NV1G2002 463 11.0 0.9 36.9% @ 10 nM 5.8 NV1G2225 464 11.2 7.85E−01 37.6% @ 10 nM 8.1 NV1G2012 465 11.3 0.7 35.8% @ 10 nM 7.5 NV1G2020 466 12 47.5 40.7% @ 10 nM 17.9 NV1G2334 467 12 5.52E−01 NV1G2025 468 12.3 0.853 7.4 73.9% @ 10 nM 7.2 NV1G2131 469 12.4 1.58 61.8% @ 10 nM 2.8 NV1G1007 470 12.5 1.3 28.1% @ 10 nM 18.0 A11I, E12T NV1G2268 471 12.5 0.861 1.8 61.8% @ 10 nM 2.7 NV1G2332 472 12.5 7.44E−01 NV1G2010 473 12.5 1.0 56.4% @ 30 nM 3.8 NV1G2053 474 12.5 33.3 73.1% @ 10 nM 2.40 NV1G1519 133 12.9 0.943 52.3% @ 10 nM 7.9 NV1G2253 475 13.5 0.695 NV1G2055 476 14.6 8.58 73.5% @ 10 nM 5.50 NV1G2338 477 14.8 6.98E−01 2.4 62.2% @ 10 nM 4.7 NV1G2030 478 15.2 1.3 9.291 68.4% @ 30 nM 4.3 NV1G2024 479 15.5 1.76 78.1% @ 30 nM 3.2 NV1G2004 480 15.6 1.4 44.1% @ 30 nM 5.9 NV1G2336 481 15.8 1.14E+00 NV1G2011 482 16.0 1.5 56.7% @ 30 nM 8.8 NV1G2080 483 16.1 1.81 13.43 70.2% @ 30 nM 4.6 NV1G2288 484 16.3 1.52 NV1G2142 485 16.4 0.834 5.3 51.2% @ 10 nM 2.9 NV1G2232 408 16.7 1.32 5.0 56.5% @ 10 nM 5.7 NV1G2193 486 16.8 1.23 43.3% @ 10 nM 11.3 NV1G2230 487 17 2.42 9.5 41.3% @ 10 nM 4.5 NV1G2182 409 17.3 1.37 3.8 54.2% @ 10 nM 5.4 NV1G1153 C- 488 29.1 0.125 5.3 66.0% @ 10 nM 5 terminal palmitoyl- lysine NV1G2339 489 18.1 1.35E+00 NV1G2016 490 18.3 1.5 71.1% @ 30 nM 5.6 NV1G2017 491 18.4 1.47 38.9% @ 30 nM 11.8 NV1G2111 492 18.5 2.06 1.4 57.3% @ 10 nM 5.6 NV1G2330 493 18.5 2.04E+00 NV1G2204 494 18.8 0.578 49.0% @ 10 nM 13.0 NV1G2026 495 18.9 1.48 80.2% @ 30 nM 2.2 NV1G1007 496 18.9 1.2 3.9 56.5% @ 10 nM 6.8 with C- terminal 5x Gly NV1G2038 497 18.9 1.46 64.8% @ 30 nM 3.3 NV1G2305 498 20.4 5.08 6.2 41.5% @ 10 nM 4.5 NV1G2021 499 20.4 1.88 39.76 60.5% @ 30 nM 6.9 NV1G2319 410 20.7 2.3 9.7 43.2% @ 10 nM 6.2 NV1G2100 500 20.8 1.65 35.2% @ 10 nM 10.8 NV1G2130 501 21.2 2.48 20.9% @ 10 nM 5.7 NV1G2081 502 21.9 1.99 29.5% @ 30 nM 10.5 NV1G2252 503 22.2 1.54 2.9 63.1% @ 10 nM 6.5 NV1G2040 504 22.7 2.17 55.5% @ 30 nM 9.1 NV1G2146 505 22.86 2.3 20.62 53.1% @ 10 nM 19.9 NV1G1153-N- 506 24 3.14 4.7 4.2 36.7% @ 10 nM 16.7 ethyl NV1G2098 507 24.1 5.44 48.4% @ 10 nM 8.4 NV1G2191 508 24.1 1.79  3.7% @ 10 nM 7.8 NV1G2333 509 24.3 2.00E+00 NV1G2224 510 24.3 1.59 10.4 34.5% @ 10 nM 7.7 NV1G1001-N- 511 25.1 2.21 4.77 74.3% @ 30 nM 1.0 ethyl NV1G1996 431 25.2 2.1 6.4 3.5 54.5% @ 30 nM 8.4 NV1G2337 512 25.6 1.10E+00 8.5 48.0% @ 10 nM 7.5 NV1G2301 513 25.7 3.83 NV1G2075 514 26.1 1.8 36.8% @ 30 nM 10.7 NV1G2278 515 26.3 3.34 1.5 58.7% @ 10 nM 5.45 NV1G2014 516 27 3.43 36.4% @ 30 nM 7.6 NV1G2065 517 27 2.53   53% @ 10 nM 2.6 NV1G2099 518 27.9 2.54 3.4 41.7% @ 10 nM 10.1 NV1G1007 519 28.4 2 5.6 31.9% @ 10 nM 16.5 E17L NV1G1007 520 29.1 2.11 G33 1007 A11I 521 29.3 2.8 9.6 38.5% @ 10 nM 5.4 NV1G2221 522 29.3 1.89 31.3% @ 10 nM 7.5 NV1G2097 523 29.9 2.92  7.0% @ 10 nM 12.2 NV1G2029 524 30.1 6.29 50.8% @ 30 nM 0.4 NV1G2257 525 30.1 1.7 4.9 50.9% @ 10 nM 8.4 NV1G1998 526 30.6 2.7  6.0% @ 30 nM 5.0 NV1G2068 527 30.7 3.11 24.0% @ 30 nM 20.0 NV1G1001 65 30.8 2.34 20.3% @ 10 nM 8.6 NV1G2137 528 30.9 6.08 NV1G2199 529 31.7 1.72 29.6% @ 10 nM 4.5 NV1G2300 530 32.6 3.69 NV1G2124 531 32.7 8.78 33.8% @ 10 nM 9.1 NV1G2254 532 32.8 3.85 34.1% @ 10 nM 10.3 NV1G2239 533 33.8 2.39 14.6 42.2% @ 10 nM 10.1 NV1G2255 534 34.2 2.55 NV1G2256 535 34.4 1.98 17.3 27.7% @ 10 nM 13.4 NV1G2095 536 35 6.48 18.8% @ 10 nM 7.2 NV1G2220 537 36.7 3.86  8.4% @ 10 nM 5.7 NV1G2154 538 37.7 2.44 12.5% @ 10 nM N/A NV1G2329 411 38 2.43E+00 NV1G2122 539 38.4 5.7 22.4% @ 10 nM 10.5 NV1G1007 C- 540 39.7 3.22 terminal palmitoyl- lysine NV1G2000 541 40.0 6.3 NV1G2009 542 40.8 3.2 NV1G2066 543 41.7 4.56 NV1G2083 544 43 3.71 NV1G2126 545 43.9 11.6  0.4% @ 10 nM 9.4 NV1G2043 370 46.4 4.09 58.7 36.5 NV1G2050 546 46.7 6.26 49.1% @ 30 nM 11.50 NV1G2071 547 47 5.73 NV1G2129 412 47.3 3.81 −6.5% @ 10 nM 6.5 NV1G2086 548 47.3 5.5 NV1G2057 341 50.6 6.33 22.2% @ 30 nM 12.20 NV1G2093 549 50.8 5.42 NV1G1995 550 51.3 3.6 NV1G2312 551 51.5 5.05 NV1G2176 552 52.9 3.3 NV1G2046 553 53.1 6.52 11.2% @ 30 nM 11.5 NV1G2047 554 53.7 4.23 40.3% @ 30 nM 12.5 NV1G2170 555 55.4 3.41 NV1G2042 556 56.5 3.71 NV1G2117 557 56.9 8.86 42.7% @ 30 nM 13.0 NV1G1999 558 57.1 18.2 NV1G2247 559 57.7 8.37 9.9 34.2% @ 10 nM 6.4 NV1G2054 560 57.8 7.98 33.0% @ 30 nM 13.40 NV1G1007 561 59.5 4.12  6.1% @ 10 nM 13.4 E17F NV1G2056 562 59.6 4.36 26.3% @ 30 nM 16.10 NV1G1007 563 63 5.52  7.4% @ 10 nM 10.2 D33 NV1G2291 413 63.3 14.9 NV1G2306 564 64.4 4.75 NV1G2023 565 66.2 9.12 NV1G2133 566 68.9 11.7 28.6% @ 10 nM 6.2 NV1G2317 568 71.2 5.72 NV1G2116 569 71.5 7.97 10.4% @ 30 nM 20.9 NV1G2174 570 72.7 6.86 NV1G2209 571 77.8 6.33 13.7 39.96% @ 10 nM  7.6 NV1G2134 572 78.3 7.06  9.9% @ 10 nM 3.5 NV1G2166 573 80.4 5.72 NV1G2119 574 82.1 21.5 NV1G2285 575 82.9 6.47 NV1G2067 576 85.2 13 NV1G2299 577 88.1 21.3 NV1G2316 578 88.5 7.99 NV1G2322 579 90 6.48 35.2% @ 10 nM 4.1 NV1G2156 414 90.5 6.88 NV1G2082 415 90.8 11.4 NV1G2165 580 91.6 6.58 NV1G2201 581 94.8 5.67 13.957% @ 10 nM  4.5 NV1G2077 582 95.4 11.9 NV1G2173 583 99.9 10.6 NV1G2207 584 20.5% @ 10 nM 4.8 64087946 417 23.8 20.7% @ 10 nM 10.9 64053366 418 22.1% @ 10 nM 3.5 64087868 585 64.9 22.9% @ 10 nM 4.2 NV1G2266 586 23.5% @ 10 nM 6.2 NV1G2287 587 24.8% @ 10 nM 8.3 64053340 419 26.8% @ 10 nM 3.7 64053236 420 28.0% @ 10 nM 13.2 64087881 589 28.4% @ 10 nM 5.4 NV1G2217 590 29.4% @ 10 nM 9.3 NV1G2183 591 31.0% @ 10 nM 7.7 64087894 592 9.4 31.0% @ 10 nM 3.8 64053223 421 33.0% @ 10 nM 5.8 NV1G2216 593 33.5% @ 10 nM 7.0 NV1G2210 594 34.3% @ 10 nM 5.5 NV1G2314 595 34.9% @ 10 nM 7.5 64032501 596 9.3 35.1% @ 10 nM 6.3 63955918 422 10.8 38.50% @ 10 nM  4.5 NV1G2088 597 41.4% @ 30 nM 4.0 NV1G2289 598 14.3 41.4% @ 10 nM 5.9 64053210 423 41.7% @ 10 nM 6.2 64053210 423 41.7% @ 10 nM 6.2 64087907 424 7.1 45.1% @ 10 nM 6.0 64032488 425 6.5 45.6% @ 10 nM 4.6 63955931 599 6.2 45.66% @ 10 nM  4.6 64053301 426 10.7 45.83% @ 10 nM  3.3 NV1G2243 600 47.6% @ 10 nM 4.8 NV1G2227 601 8.1 47.7% @ 10 nM 6.3 64053275 427 2.9 48.22% @ 10 nM  5.2 64053275 427 2.9 48.22% @ 10 nM  5.2 64087920 602 2.6 50.3% @ 10 nM 8.9 64053327 428 7.9 51.9% @ 10 nM 2.6 NV1G2233 603 52.8% @ 10 nM 2.0 NV1G2265 604 53.1% @ 10 nM 7.0 NV1G2172 605 54.4% @ 30 nM 6.7 NV1G2248 606 5.2 54.8% @ 10 nM 3.6 NV1G2229 608 55.9% @ 10 nM 7.0 NV1G2324 429 57.5% @ 10 nM 3.9 NV1G2096 610 61.5% @ 30 nM 22.8 NV1G2094 430 63.2% @ 30 nM 6.2 NV1G2039 (- 611 1.9 78.9% @ 10 nM 2.5 GP) 63930854 612 5.1 63909404 613 9.1 63930880 614 12.2 63909378 615 12.5 63930841 416 20.9 NV1G714 616 1.3 1.4 NV1G690 617 1.9 1.2 NV1G688 618 2.2 0.4 NV1G700 619 2.5 1.3 NV1G692 620 2.8 1.4 NV1G1051 621 5.0 3.0 38.6% @ 10 nM 8.5 NV1G702 622 5.5 4.0 62.8% @ 10 nM 5.8 NV1D1328_1 623 6.4 1.5 NV1G694 624 24.1 23.5 NV1D1339_1 625 21.5% @ 10 nM 13.6 NV1G698 626 22.8% @ 10 nM NV1G1055 627 22.9% @ 10 nM 3.6 NV1G1635 628 24.3% @ 10 nM 10.0 NV1G224 629 24.4% @ 20 nM NV1G704 630 24.8% @ 3 nM  2.7 NV1D1335_1 631 25.0% @ 10 nM NV1G1057 632 26.7% @ 10 nM 5.4 NV1G217 633 30.8% @ 10 nM 2.7 NV1G225 634 30.8% @ 10 nM 5.9 NV1G696 635 31.1% @ 10 nM NV1D1331_1 636 43.7% @ 10 nM NV1G1047 637 47.7% @ 10 nM 6.5 NV1G576 638 60.1% @ 10 nM NV1G581 639 60.2% @ 10 nM 6.0 NV1G2349 642 10.1% @ 10 nM 7.9 NV1G585 643 16.2% @ 10 nM 13.1 64151490 644 32.5 18.3% @ 10 nM 20.5 NV1G587 645 20.6% @ 10 nM 12.8 NV1G2352 646 23.4% @ 10 nM 9.2 NV1G2035 647 27.7% @ 10 nM 6.7 NV1G2351 648 28.9% @ 10 nM 9.3 NV1G2346 649 33.6% @ 10 nM 12.4 NV1G2341 650 35.8% @ 10 nM 2.2 NV1G2342 651 39.2% @ 10 nM 13.0 NV1G2348 652 41.7% @ 10 nM 10.8 NV1G1934 653 53.0% @ 10 nM 6.1 NV1G2347 654 56.3% @ 10 nM 14.8 NV1G584 655 56.4% @ 10 nM 4.9 NV1G2033 656 59.1% @ 10 nM 3.6 NV1G2343 657 59.6% @ 10 nM 3.5 NV1G2344 658   63% @ 10 nM 3.8 NV1G2345 659 64.8% @ 10 nM 10.4 NV1G2034 660  7.0% @ 10 nM 3.6 NV1G594 661 NV1G1041 662

Example 9. Generation of Variants of 63955918

Protoxin-II variant 63955918 has W7Q and W30L substitutions when compared to the wild type Protoxin-II. As described in Example 6, mutation of both Trp7 and Trp30 alone or in combination improves folding of the resulting Protoxin-II variants, and could rescue folding of difficult-to-refold Protoxin-II variants.

Additional variants were generated onto the 63955918 backbone to evaluate possibility of further improving characteristics of the molecule. Some variants are also described in Examples 6 and 7.

The generated variants and their sequences are shown in Table 20.

TABLE 20 SEQ ID Mutations ID NO: Sequence 64053366 Protoxin-II 418 YCQKWMQTCDDERKCCEGMVCRLWCKKKLL- W7Q S11D COOH W30L (−GP) 64053340 Protoxin-II 419 YCQKWMQTCDSERFCCEGMVCRLWCKKKLL- W7Q K14F COOH W30L (−GP) 64053236 Protoxin-II 420 GPYCQKWMQTCDSERFCCEGMVCRLWCKKKLL- W7Q K14F COOH W30L (+GP) 64053223 Protoxin-II 421 GPYCQKWMQTCDIERKCCEGMVCRLWCKKKLL- W7Q S11I COOH W30L (+GP) 64053210 Protoxin-II 423 GPYCQKWMQTCDSERKCCNGMVCRLWCKKKLL- W7Q E17N COOH W30L (+GP) 64053301 Protoxin-II 426 GPYCQKWMQTCDVERKCCEGMVCRLWCKKKLL- W7Q S11V COOH W30L (+GP) 64053275 Protoxin-II 427 GPYCQKWMQTCDSERKCCLGMVCRLWCKKKLL- W7Q E17L COOH W30L (+GP) 64053327 Protoxin-II 428 YCQKWMQTCDSERKCCNGMVCRLWCKKKLL- W7Q E17N COOH W30L (−GP) 64159108 nerve labeling 663 SHSNTQTLAKAPEHTGAPAPAPAPAPYCQKWMQTC peptide-5xAP- DSERKCCEGMVCRLWCKKKLL-COOH Protoxin-II W7Q W30L 64151477 Protoxin-II 664 YCQKWMQTCDSYRFCCEGMVCRLWCKKKLL-NH- W7Q W30L methyl K14F E12Y N- methyl (−GP) 64053288 Protoxin-II 665 GPYCQEWMQTCDSERKCCRGMVCRLWCKKKLL- W7Q K4E E17R COOH W30L (+GP) 64106666 Protoxin-II 666 YCQKWMQTCDSERKCCLGMVC-(4-guanidino-L- W7Q E17L phenylalanine)-LWCKKKLL-COOH W30L R22F(Guanidino) (−GP) 64159134 Protoxin-II 667 YCQKWMQTCDSERKCCEGMVC-(4-guanidino-L- W7Q W30L phenylalanine)-LWCKKKLL-COOH R22F(Guanidino) (−GP) 64106575 Protoxin-II 668 YCQKWMQTCDVERKCCLGMVCRLWCKKKLL- W7Q E17L COOH W30L S11V (−GP) 64106627 Protoxin-II 669 YCQKWMQTCDSERKCCLPMVCRLWCKKKLL-COOH W7Q E17L W30L G18P (−GP) 64106640 Protoxin-II 670 YCQKWMQTCDSERKCCLGMVC-(N-omega- W7Q E17L methyl-L-arginine)-LWCKKKLL-COOH W30L R22Me (−GP) 64106653 Protoxin-II 671 YCQKWMQTCDSERKCCLGMVC-(N-omega, N- W7Q E17L omega-dimethyl(asymmetric)-L-arginine)- W30L LWCKKKLL-COOH R22Me(2) (−GP) 64159121 Protoxin-II WW 672 GPYCQKWMQTCDSERKCCEGMVC-(N-omega- R22Me (+GP) methyl-L-arginine)-LWCKKKLL-COOH 64106757 Protoxin-II 673 YCYKWMQTCDSERKCCEGMVCRLWCKKKLL-COOH W7Q W30L Q3Y (−GP) 64106744 Protoxin-II 674 YCQKWMQTCDSERKCCEPMVCRLWCKKKLL- W7Q W30L COOH G18P (−GP) 64106705 Protoxin-II 675 YCQKWMQTCDSERKCCLGMVCRLWCKKKLL- W7Q W30L COOH E17L (−GP) 64106718 Protoxin-II 676 YCQKWMQTCDSERKCCQGMVCRLWCKKKLL- W7Q W30L COOH E17Q (−GP) 64170171 Protoxin-II 677 YCQKWMQTCDSERKCC-(Glutamyl-4- W7Q W30L aminobutane)-GMVCRLWCKKKLL-COOH E17glutamyl-4- aminobutane (−GP) 64106731 Protoxin-II 678 YCQKWMQTCDSYRKCCEGMVCRLWCKKKLL- W7Q W30L COOH E12Y (−GP) 64159082 Protoxin-II 679 GPYCQKWMQTCDSERKCCEGMVCRLWCKKKLL- W7Q W30L OH Leucinol (+GP) 64151503 Protoxin-II 680 HLNILSTLWKYRGPYCQKWMQTCDSERKCCEGMVC W7Q W30L RLWCKKKLL-COOH Teti 64151438 Protoxin-II 681 YCQKWMQTCDSERKCCEGMVCRLWCKKKLL-NH- W7Q W30L N- methyl methyl (−GP) 64151464 Protoxin-II 682 YCQKWMQTCDSERFCCEGMVCRLWCKKKLL-NH- W7Q W30L methyl K14F N-methyl (−GP) 64170145 Protoxin-II 683 YCQKWMQTCDS-(Glutamyl-4-aminobutane)- W7Q W30L RKCCEGMVCRLWCKKKLL-COOH E12glutamyl-4- aminobutane(−GP) 64170132 Protoxin-II 684 YCQKWMQTC-(Asparagyl-4-aminobutane)- W7Q W30L SERKCCEGMVCRLWCKKKLL-COOH D10asparagyl- 4-aminobutane (−GP) 64106601 Protoxin-II 685 YCQKWMQTCDSERFCCLGMVCRLWCKKKLL- W7Q E17L COOH W30L K14F (−GP)

The variants were characterized as described above. Table 21 shows the IC₅₀ values and/or percent block (% blk) (% inhibition of currents in comparison to a control sample). Se: standard error.

TABLE 21 Nav1.7 VERA- TRIDINE- INDUCED DE- POLAR- IZATION QP Protein SEQ IC₅₀ IC₅₀ ID ID NO: (nM) ± (nM) se % blk se 64053366 418 22.1% @ 10 nM 3.5 64053340 419 33.0 29.58% @ 10 nM  4.2 64053236 420 28.0% @ 10 nM 13.2 64053223 421 33.0% @ 10 nM 5.8 64053210 423 41.7% @ 10 nM 6.2 64053301 426 10.7 45.83% @ 10 nM  3.3 64053275 427 4.9 48.69% @ 10 nM  4.1 64053327 428 7.9 51.9% @ 10 nM 2.6 64159108 663 53.5 13.3% @ 10 nM 9.7 64151477 664 400.4 14.4% @ 30 nM 4.8 64053288 665 17.8% @ 10 nM 4.1 64106666 666 36.3 19.6% @ 10 nM 5.4 64159134 667 131.7 21.3% @ 30 nM 3.2 64106575 668 18.1 23.57% @ 10 nM  6.5 64106627 669 32.4 26.3% @ 10 nM 3.0 64106640 670 19.3 26.3% @ 10 nM 4.6 64106653 671 20.4 26.4% @ 10 nM 6.6 64159121 672 44.2 36.1% @ 30 nM 11.2 64106757 673 14.4 37.0% @ 10 nM 2.2 64106744 674 11.1 39.0% @ 10 nM 3.4 64106705 675 8.8 41.6% @ 10 nM 4.3 64106718 676 11.4 43.5% @ 10 nM 5.7 64170171 677 6.2 56.7% @ 10 nM 6.9 64106731 678 3.7 64.3% @ 10 nM 4.9 64159082 679 3.6 65.5% @ 10 nM 8.0 64151503 680 3.6 65.5% @ 10 nM 8.0 64151438 681 2.5 66.2% @ 10 nM 7.1 64151464 682 5.6 67.3% @ 10 nM 8.8 64170145 683 2.2 75.0% @ 10 nM 4.4 64170132 684 1.2 78.4% @ 10 nM 3.7 64106601 685

Example 10. Generation of Variants of 63955918

Additional variants of 63955918 were designed in order to improve biodistribution of the resulting peptides.

W7 and W30 substitutions were also designed on a variety of family 3 inhibitory cysteine knot peptides to assess whether the improved selectivity and improved refolding properties conferred by those mutations extended beyond Protoxin-II to other highly homologous peptide sequences. Family 3 spider toxins that inhibit Nav channels (NaSpTx) as defined by Klint et. al. (Toxicon 60:478-491, 2012), were chosen as scaffolds for incorporation of Q at position 7 and L at position 30 (numbering based on Seq ID 1), and include). These sequences include beta-theraphotoxin-Gr1c, beta-theraphotoxin-Gr1e, beta/kappa-theraphotoxin-Cg2a, kappa-theraphotoxin-Ps1a, kappa-theraphotoxin-Ps1b, kappa-theraphotoxin-Gr2b, kappa-theraphotoxin-Gr2c, kappa-theraphotoxin-Gr2d, kappa-theraphotoxin-Cg2a, kappa-theraphotoxin-Cg2b, kappa-theraphotoxin-Ec2c, beta-theraphotoxin-Gr1d, beta/kappa-theraphotoxin-Pm2a, kappa-theraphotoxin-Ec2a and kappa-theraphotoxin-Ec2b.

Additional family 3 NaSpTx scaffolds for mutation were identified in Arachnoserver (http://_www_arachnoserver_org/_mainMenu_html. Alignment of the family 3 toxins is shown in FIG. 14.

Table 22 shows the sequences of the designed variants.

TABLE 22 SEQ ID Protein ID Mutations NO: Protein sequence (L-Lys(N-epsilon- N-terminal 686 (L-Lys(N-epsilon- (N-alpha- addition of (L- (N-alpha- Palmitoyl-L- Lys(N-epsilon-(N- Palmitoyl-L- gamma glutamyl))- alpha-Palmitoyl- gamma-glutamyl))- PEG(2)-Protoxin- L-gamma- PEG(2)- II-W7Q W30L glutamyl))- YCQKWMQTCDSERKCCE PEG(2)on GMVCRLWCKKKLL- Protoxin-II W7Q COOH W30L (L-Lys(N-epsilon- N-terminal 687 (L-Lys(N-epsilon- (N-alpha- addition of (L- (N-alpha- Palmitoyl-L- Lys(N-epsilon-(N- Palmitoyl-L- gamma-glutamyl))- alpha-Palmitoyl- gamma-glutamyl))- GGGGS-Protoxin-II L-gamma- GGGGS- W7Q W30L glutamyl))GGGGS YCQKWMQTCDSERKCCE on Protoxin-II GMVCRLWCKKKLL- W7Q W30L COOH (L-Lys(N-epsilon- N-terminal 688 (L-Lys(N-epsilon- (N-alpha- addition(L-Lys(N- (N-alpha- Palmitoyl-L- epsilon-(N-alpha- Palmitoyl-L- gamma-glutamyl))- Palmitoyl-L- gamma-glutamyl))- PEG(2)-Protoxin- gamma-glutamyl))- PEG(2)- II W7Q W30L K14F PEG(2) on YCQKWMQTCDSERFCCE Protoxin-IIW7Q GMVCRLWCKKKLL- W30L K14F COOH (L-Lys(N-epsilon- N-terminal 689 (L-Lys(N-epsilon- (N-alpha- addition of (L- (N-alpha- Palmitoyl-L- Lys(N-epsilon-(N- Palmitoyl-L- gamma-glutamyl))- alpha-Palmitoyl- gamma-glutamyl))- GGGGS-Protoxin-II L-gamma- GGGGS- W7Q W30L K14F glutamyl))-GGGGS- YCQKWMQTCDSERFCCE on Protoxin-II GMVCRLWCKKKLL- W7Q W30L K14F COOH Protoxin-II W7Q Protoxin-II W7Q 690 YCQKWMQTC- W30L K14F W30L K14F (Asparagy1-4- D10asparagy1-4- D10asparagyl-4- aminobutane)- aminobutane (−GP) aminobutane (−GP) SERFCCEGMVCRLWCKK KLL-COOH Protoxin-II W7Q Protoxin-II W7Q 691 YCQKWMQTCDSERKCCE W30L G18P N W30L G18P N- PMVCRLWCKKKLL-N- methyl methyl Me Protoxin-II W7Q Protoxin-II W7Q 692 (4-bromo-L- W30L Y1--> 4- W30L Y1--> 4- phenylalanine)- bromo-Phe bromo-Phe CQKWMQTCDSERKCCEG MVCRLWCKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 693 YCQK-(5-bromo-L- W30L W5--> 5- W30L W5--> 5- tryptophan) bromo-Trp bromo-Trp CQKWMQTCDSERKCCEG MVCRLWCKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 694 YCQKWMQTCDSERKCCE W30L W24--> 5- W30L W24--> 5- GMVCRL-(5-bromo- bromo-Trp bromo-Trp L-tryptophan)- CKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 695 (4-chloro-L- W30L Y1-->4- W30L Y1-->4- phenylalanine)- chloro-Phe chloro-Phe CQKWMQTCDSERKCCEG MVCRLWCKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 696 (3-chloro-L- W30L Y1-->3- W30L Y1-->3- tyrosine)- chloro-Tyr chloro-Tyr CQKWMQTCDSERKCCEG MVCRLWCKKKLL-COOH β/κ- β/κ- 697 YCQKWMQTCDSKRACCE theraphotoxin- theraphotoxin- GLECKLWCRKIWL-NH2 Cg2a W7Q, R20E, Cg2a W7Q, R20E, 129W, addition of 129W, addition of L30 L30 β-theraphotoxin- β-theraphotoxin- 698 YCQKWMQTCDSKRKCCE Grlc W7Q G30L Grlc W7Q G30L DMVCQLWCKKRLL- COOH β-theraphotoxin- β-theraphotoxin- 699 YCQKWMQTCDSERKCCE Grle W7Q W30L Grle W7Q W30L DMVCELWCKKRLL- COOH β/κ- β/κ- 700 YCQKWMQTCDSKRACCE theraphotoxin- theraphotoxin- GLRCKLWCRKIIL- Cg2a W7Q addition Cg2a W7Q addition COOH of L30 of L30 κ-theraphotoxin- κ-theraphotoxin- 701 YCQKWMQTCDSARKCCE Psla W7Q addition Psla W7Q addition GLVCRLWCKKIIL- of L30 of L30 COOH κ-theraphotoxin- κ-theraphotoxin- 702 YCQKWMQTCDEERKCCE Ps1b W7Q N30L Pslb W7Q N30L GLVCRLWCKRIILM- COOH κ-theraphotoxin- κ-theraphotoxin- 703 YCQKWMQTCDEERKCCE Gr2b W7Q E30L Gr2b W7Q E30L GLVCRLWCKKKILEG- COOH κ-theraphotoxin- κ-theraphotoxin- 704 YCQKWMQTCDEERKCCE Gr2c W7Q E30L Gr2c W7Q E30L GLVCRLWCKKKILW- COOH κ-theraphotoxin- κ-theraphotoxin- 705 YCQKWMQTCDEERKCCE Gr2d W7Q R30L Gr2d W7Q R30L GLVCRLWCKKKNLVVIS GEDTKLPTLKIQLMKSN ITDI-COOH κ-theraphotoxin- κ-theraphotoxin- 706 YCQKWMQTCDSERKCCE Cg2a W7Q addition Cg2a W7Q addition GYVCELWCKYNLL- of L30 of L30 COOH κ-theraphotoxin- κ-theraphotoxin- 707 YCQKWMQTCDSERKCCE Cg2b W7Q G30L Cg2b W7Q G30L GYVCELWCKYNML- COOH (L-Lys(N-epsilon- Addition of N- 708 (L-Lys(N-epsilon- (N-alpha- terminal (L- (N-alpha- Palmitoyl-L- Lys(N-epsilon-(N- Palmitoyl-L- gamma-glutamyl))- alpha-Palmitoyl- gamma-glutamyl))- Protoxin-II W7Q L-gamma- YCQKWMQTCDSERKCCE W30L glutamyl)) on GMVCRLWCKKKLL- Protoxin-II W7Q COOH W30L Protoxin-II W7Q W7Q W30L S11-- 709 YCQKWMQTCD-(beta- W30L S11-->beta- >beta-chloro-Ala chloro-L- chloro-Ala alanine)- ERKCCEGMVCRLWCKKK LL-COOH Protoxin-II W7Q Protoxin-II W7Q 710 YCQKWMQTCDSERKCCE W30L-PEG(2)-(L- W30L with GMVCRLWCKKKLL- Lys(N-epsilon-(N- addition of C- 2xPEG-(L-Lys(N- alpha-Palmitoyl- terminal PEG(2)- epsilon-(N-alpha- L-gamma- (L-Lys(N-epsilon- Palmitoyl-L- glutamyl)) (N-alpha- gamma-glutamyl))- Palmitoyl-L- COOH gamma-glutamyl)) Protoxin-II W7Q Protoxin-II W7Q 711 YCQKWMQTCDSERKCCE W30L-GGGGS-(L- W30L with C- GMVCRLWCKKKLL- Lys(N-epsilon-(N- terminal GGGGS- GGGGS-(L-Lys(N- alpha-Palmitoyl- (L-Lys(N-epsilon- epsilon-(N-alpha- L-gamma- (N-alpha- Palmitoyl-L- glutamyl)) Palmitoyl-L- gamma-glutamyl))- gamma-glutamyl)) COOH Protoxin-II W7Q Protoxin-II W7Q 712 (4-bromo-L- W30L (Y1-->4- W30L (Y1-->4- phenylalanine)- bromo-Phe), (S11- bromo-Phe), (S11- CQKWMQTCD-(beta- ->beta-chloro- ->beta-chloro- chloro-L- Ala) Ala) alanine)- ERKCCEGMVCRLWCKKK LL-COOH Protoxin-II W7Q Protoxin-II W7Q 713 (4-bromo-L- W30L (Y1-->4- W30L (Y1-->4- phenylalanine)- bromo-Phe), (S11- bromo-Phe), (S11- CQKWMQTCD-(beta- ->beta-chloro- ->beta-chloro- chloro -L- Ala), (W24-->5- Ala), (W24-->5- alanine)- bromo-Trp) bromo-Trp) ERKCCEGMVCRL-(5- bromo-L- tryptophan)- CKKKLL-COOH WW (S11-->beta- WW (S11-->beta- 714 YCQKWMQTCD-(beta- chloro-Ala), chloro-Ala), chloro -L- (W24-->5-bromo- (W24-->5-bromo- alanine) - Trp) Trp) ERKCCEGMVCRL-(5- bromo-L- tryptophan)- CKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 715 YCQKWMQTCD- W30L S11(L-Lys(N- W30L S11(L-Lys(N- (Lys(N-epsilon- epsilon-(N-alpha- epsilon-(N-alpha- (N-alpha- Palmitoyl-L- Palmitoyl-L- Palmitoyl-L- gamma-glutamyl)) gamma-glutamyl)) gamma-glutamyl))- ERKCCEGMVCRLWCKKK LL-COOH Protoxin-II W7Q Protoxin-II W7Q 716 YCQKWMQTCDS- W30L E12(L-Lys(N- W30L E12(L-Lys(N- (Lys(N-epsilon- epsilon-(N-alpha- epsilon-(N-alpha- (N-alpha- Palmitoyl-L- Palmitoyl-L- Palmitoyl-L- gamma-glutamyl)) gamma-glutamyl)) gamma-glutamyl))- RKCCEGMVCRLWCKKKL L-COOH WW E17(L-Lys(N- WW E17(L-Lys(N- 717 YCQKWMQTCDSERKCC- epsilon-(N-alpha- epsilon-(N-alpha- (Lys(N-epsilon- Palmitoyl-L- Palmitoyl-L- (N-alpha- gamma-glutamyl)) gamma-glutamyl)) Palmitoyl-L- gamma-glutamyl))- GMVCRLWCKKKLL- COOH Protoxin-II W7Q Protoxin-II W7Q 718 YCQKWMQTC-(L- W30L D10 L- W30L D10-(L- asparagy1-4- asparagy1-4- asparagy1-4- aminobutane)-S- aminobutane E12 aminobutane E12 (L-glutamyl-4- L-glutamyl-4- L-glutamyl-4- aminobutane)- aminobutane E17 aminobutane E17 RKCC-(L-glutamyl- L-glutamyl-4- L-glutamyl-4- 4-aminobutane)- aminobutane aminobutane GMVCRLWCKKKLL- COOH Protoxin-II W7Q Protoxin-II W7Q 719 (4-bromo-L- W30L (Y1-->4- W30L (Y1-->4- phenylalanine)- bromo-Phe), (W5-- bromo-Phe), (W5-- CQK-(5-bromo-L- >5-bromo-Trp) >5-bromo-Trp) tryptophan)- (W24-->5-bromo- (W24-->5-bromo- MQTCDSERKCCEGMVCR Trp) Trp) L-(5-bromo-L- tryptophan)- CKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 720 (4-bromo-L- W30L (Y1-->4- W30L (Y1-->4- phenylalanine)- bromo-Phe), (W24- bromo-Phe), (W24- CQKWMQTCDSERKCCEG ->5-bromo-Trp) ->5-bromo-Trp) MVCRL-(5- bromotryptophan)- CKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 721 (3,4-dichloro-L- W30L Y1-->3,4 di- W30L Y1-->3,4 di- phenylalanine)- chloro-Phe chloro-Phe CQKWMQTCDSERKCCEG MVCRLWCKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 722 (3,5-dibromo-L- W30L Y1-->3,5 di- W30L Y1-->3,5 di- tyrosine)- bromo-Tyr bromo-Tyr CQKWMQTCDSERKCCEG MVCRLWCKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 723 (3,4,5-trifluoro- W30L Y1-->3,4,5 W30L Y1-->3,4,5 L-phenylalanine)- tri-fluoro-Phe tri-fluoro-Phe CQKWMQTCDSERKCCEG MVCRLWCKKKLL-COOH Protoxin-II W7Q Protoxin-II W7Q 724 (L-cyano-beta- W30L with W30L with alanine)- additional N- additional N- YCQKWMQTCDSERKCCE terminal L-cyano- terminal L-cyano- GMVCRLWCKKKLL- beta-alanine beta-alanine COOH Protoxin-II W7Q Protoxin-II W7Q 725 (propargylglycine)- W30L with W30L with YCQKWMQTCDSERKCCE additional N- additional N- GMVCRLWCKKKLL- terminal L- terminal L- COOH propargylglycine propargylglycine Protoxin-II W7Q Protoxin-II W7Q 726 (L-norvaline)- W30L with W30L with YCQKWMQTCDSERKCCE additional N- additional N- GMVCRLWCKKKLL- terminal L- terminal L- COOH norvaline norvaline κ-theraphotoxin- κ-theraphotoxin- 727 YCQFKMQTCDSERKCCE Ec2c W7Q addition Ec2c W7Q addition DMVCRLWCKLNLL- of L30 of L30 COOH β-theraphotoxin- β-theraphotoxin- 728 YCQKWMQTCDSERKCCE Grid W7Q G30L Grid W7Q G30L DMVCRLWCKKRLL- COOH β/κ- β/κ 729 YCQEFLQTCDEERKCCG Theraphotoxin- Theraphotoxin- DMVCRLWCKKRLL- Pm2a W7Q addition Pm2a W7Q addition COOH of L30 of L30 κ-theraphotoxin- κ-theraphotoxin- 730 YCQKFLQTCDTERKCCE Ec2a W7Q addition Ec2a W7Q addition DMVCELWCKLEKL- of L30 of L30 COOH κ-theraphotoxin- κ-theraphotoxin- 731 YCQKFLQTCDTERKCCE Ec2b W7Q addition Ec2b W7Q addition DMVCELWCKYKEL- of L30 of L30 COOH Protoxin-II WQ W7Q W30L E12Y N- 732 YCQKWMQTCDSYRKCCE W30L E12Y N- methyl GMVCRLWCKKKLL-N- methyl Me Protoxin-II W7Q W7Q W30L Q3Y N- 733 YCYKWMQTCDSERKCCE W30L Q3Y N-methyl methyl GMVCRLWCKKKLL-N- Me Protoxin-II W7Q W7Q W30Y 734 YCQKWMQTCDSERKCCE W30Y GMVCRLWCKKKLY- COOH Protoxin-II W7Q W7Q W30F 735 YCQKWMQTCDSERKCCE W30F GMVCRLWCKKKLF- COOH Protoxin-II W7Q W7Q W30norvaline 736 YCQKWMQTCDSERKCCE W30norvaline GMVCRLWCKKKL-(L- norvaline)--COOH

The resulting variants incorporating non-natural amino acids are generated by standard solid-phase peptide synthesis and oxidative refolding methods.

The variants having peg group attached are generated via standard chemical conjugation methods.

The resulting variants are tested for their ability to inhibit Nav1.7 in veratridine-induced depolarization inhibition and QPatch assays as described in Example 3.

The generated variants are tested for their selectivity using methods described in Example 3. 

We claim:
 1. An isolated Protoxin-II variant that inhibits human Nav1.7 activity, the Protoxin-Ill variant comprising: a W30L substitution; and a second substitution comprising at least one of position Y1X, W7Q, S11X, E12R, E12N, E12K, E12T, E12Q, E12Y, E12 glutamyl-4-aminobutane, K14X, E17X, G18X, M19F, R22X and L29V, when residue numbering is according to SEQ ID NO: 1, wherein X is individually selected from a natural amino acid and a non-natural amino acid.
 2. An isolated Protoxin-II variant that inhibits human Nav1.7 activity, wherein the Protoxin-II variant comprises a modification of SEQ ID NO: 1, the modification comprising at least one of: a) W7Q and Q3Y substitutions, b) W7Q and D10 asparagyl-4-aminobutane substitutions, c) W7Q and S11I substitutions, d) W7Q and S11V substitutions, e) W7Q and E12Y substitutions, f) W7Q and E12 glutamyl-4-aminobutane substitutions, g) W7Q and K14F substitutions, h) W7Q and E17L substitutions, i) W7Q and E17N substitutions, j) W7Q and E17 glutamyl-4-aminobutane substitutions, k) W7Q and G18P substitutions, l) W7Q and R22N-omega methyl-L-arginine substitutions, m) W7Q and L29V substitutions, and n) W7Q and W30L substitutions, wherein residue numbering is according to SEQ ID NO:
 1. 3. The isolated Protoxin-II variant of claim 2, comprising the sequence X₁X₂X₃CX₄X₅WX₆QX₇CX₈X₉X₁₀X₁₁X₁₂CCX₁₃X₁₄X₁₅X₁₆CX₁₇LWCX₁₈KKLX₁₉ (SEQ ID NO: 432), X₁ is G, P, A or deleted; X₂ is P, A or deleted; X₃ is S, Q, A, R or Y; X₄ is Q, R, K, A, S or Y; X₅ is K, S, Q or R; X₆ is M or F; X₇ is T, S, R, K or Q; X₈ is D, T, or asparagyl-4-aminobutane; X₉ is S, A, R, I or V; X₁₀ is E, R, N, K, T, Q, Y or glutamyl-4-aminobutane; X₁₁ is R or K; X₁₂ is K, Q, S, A or F; X₁₃ is E, Q, D, L, N, or glutamyl-4-aminobutane; X₁₄ is G, Q or P; X₁₅ is M or F; X₁₆ is V or S; X₁₇ is R, T or N-omega methyl-L-arginine; and X₁₈ is K or R; X₁₉ is W or L; and optionally having an N-terminal extension or a C-terminal extension.
 4. The Protoxin-II variant of claim 2, further comprising: a substitution at at least one of residue Y1, S11, E12, K14, E17, G18, L29 and W30, wherein said substitution comprises at least one of a natural amino acid and a non-natural amino acid.
 5. The Protoxin-II variant of claim 2, comprising: a W7Q substitution; a W30L substitution; and a third substitution at at least one of residue Y1, S11, E12, K14, E17, G18, M19 and L29; and wherein said third substitution comprises at least one of a natural amino acid and a non-natural amino acid.
 6. The Protoxin-II variant of claim 2, comprising: a substitution W30L a substitution WQ7; and at least 90% identity to SEQ ID NO: 422 (GPYCQKWMQTCDSERKCCEGMVCRLWCKKKLL-COOH), when residue numbering is according to SEQ ID NO:
 1. 7. The Protoxin-Ill variant of claim 2, comprising the sequence X₁X₂X₃CQKWMQTCDX₄X₅RX₆CCX₇X₈X₉VCRLWCKKKX₁₀X₁₁ (SEQ ID NO: 737); wherein X₁ is G, P, A or deleted; X₂ is P, A or deleted; X₃ is S, Q, A, R or Y; X₄ is S, A, R, I or V; X₅ is E, R, N, K, T, Q, Y or glutamyl-4-aminobutane; X₆ is K, Q, S, A or F; X₇ is E, Q, D, L, N or glutamyl-4-aminobutane; X₈ is G, Q or P; X₉ is M or F; X₁₀ is L, V; and X₁₁ is W or L.
 8. The isolated Protoxin-II variant of claim 2, wherein the variant inhibits Nav1.7 activity by at least 25%, when the Nav1.7 activity is measured using a patch clamp assay using an extracellular solution containing 137 mM NaCl, 5.4 mM KCl, 1 mM MgCl₂, 2 mM CaCl₂, 5 mM glucose, and 10 mM HEPES, pH=7.4 and osmolarity=315 mOsm, an intracellular solution containing 135 mM CsF, 10 mM CsCl, 5 mM EGTA, 5 mM NaCl and 10 mM HEPES, pH=7.3 and osmolarity=290 mOsm and a holding potential of −75 mV.
 9. The isolated Protoxin-II variant of claim 2, comprising the amino acid sequence GPQCX₁X₂WX₃QX₄CX₅X₆X₇X₈X₉CCX₁₀X₁₁FX₁₂CX₁₃LWCX₁₄KKLL (SEQ ID NO: 433), wherein X₁ is Q, R, K, A or S; X₂ is K, S, Q or R; X₃ is M or F; X₄ is T, S, R, K or Q; X₅ is D or T; X₆ is S, A or R; X₇ is E, R, N, K, T or Q; X₈ is R or K; X₉ is K, Q, S or A; X₁₀ is E, Q or D; X₁₁ is G or Q; X₁₂ is V or S; X₁₃ is R or T; and X₁₄ is K or R.
 10. The isolated Protoxin-II variant of claim 2, comprising the amino acid sequence of SEQ ID NOs: 417,418, 419, 420, 421, 422, 423, 425, 426, 427, 428, 443, 455, 470, 519, 521, 585, 589, 592, 596, 599, 612, 613, 614, 615, 624, 644, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680,681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 694, 695, 696, 708, 709, 710,711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 732, or
 733. 11. The isolated Protoxin-II variant of claim 2, further comprising at least one of a free C-terminal carboxylic acid, amide, methylamide or butylamide group.
 12. The isolated Protoxin-II variant of claim 2, that inhibits human Nav1.7 activity with an IC₅₀ value of about 3×10⁻⁸ M or less, wherein the IC₅₀ value is measured using a veratridine-induced depolarization inhibition assay using fluorescence resonance energy transfer (FRET) in the presence of 25×10⁻⁶ M 3-veratroylveracevine in HEK293 cells stably expressing human Nav1.7.
 13. The isolated Protoxin-II variant of claim 12 inhibits human Nav1.7 activity with an IC₅₀ value of between about 3×10⁻⁸ M to about 1×10⁻⁹ M.
 14. An isolated fusion protein comprising the Protoxin-II variant of claim 2 conjugated to a half-life extending moiety.
 15. The fusion protein of claim 14, wherein the half-life extending moiety is human serum albumin (HSA), albumin binding domain (ABD), Fc or polyethylene glycol (PEG).
 16. The Protoxin-II variant of claim 2, further comprising: at least one linker; and at least one of an N-terminal extension conjugated via the linker and a C-terminal extension conjugated via the linker.
 17. The Protoxin-II variant of claim 16, wherein the N-terminal extension comprises at least one of SEQ ID NOs: 372, 373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384 and
 385. 18. The Protoxin-II variant of claim 16, wherein the C-terminal extension comprises at least one of SEQ ID NOs: 374, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396 and
 397. 19. The Protoxin-II variant of claim 16, wherein the linker comprises at least one of SEQ ID NOs: 383, 392, 398, 399, 400, 401 and
 402. 20. A pharmaceutical composition comprising: at least one of the isolated Protoxin-II variant of claim 2 an isolated fusion protein, wherein the isolated fusion protein comprises the Protoxin-II variant of claim 1 conjugated to a half-life extending moiety; and a pharmaceutically acceptable excipient.
 21. An isolated polynucleotide encoding the Protoxin-Ill variant of claim
 2. 22. A vector comprising the isolated polynucleotide of claim
 21. 23. A host cell comprising the vector of claim
 22. 24. A method of producing an isolated Protoxin-II variant, comprising culturing the host cell of claim 23 and recovering the Protoxin-II variant produced by the host cell.
 25. A method of treating pain in a subject, comprising: administering to a subject perceiving pain as a result of Nav1.7 channel activity a therapeutically effective amount of a therapeutic composition comprising at least one of the Protoxin-II variant of claim 2 and an isolated fusion protein, wherein the isolated fusion protein comprises the Protoxin-II variant of claim 2 conjugated to a half-life extending moiety, and wherein the therapeutically effective amount treats the pain by at least partially preventing the perception of the pain.
 26. The method of claim 25, wherein the subject is a human.
 27. The method of claim 25, wherein pain is chronic pain, acute pain, neuropathic pain, cancer pain, nociceptive pain, visceral pain, back pain, post-operative pain, thermal pain, phantom limb pain, or pain associated with inflammatory conditions, primary erythemalgia (PE), paraoxysmal extreme pain disorder (PEPD), osteoarthritis, rheumatoid arthritis, lumbar discectomy, pancreatitis, fibromyalgia, painful diabetic neuropathy (PDN), post-herpetic neuropathy (PHN), trigeminal neuralgia (TN), spinal cord injuries or multiple sclerosis.
 28. The method of claim 27, wherein the Protoxin-Ill variant is administered peripherally.
 29. The method of claim 28, wherein the Protoxin-II variant is administered locally to a joint, spinal cord, surgical wound, sites of injury or trauma, peripheral nerve fibers, urogenital organs, or inflamed tissues. 